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JP2017049202

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DESCRIPTION JP2017049202
Abstract: A pressure sensor, a microphone, a blood pressure sensor and a touch panel capable of
expanding a dynamic range are provided. According to an embodiment, a pressure sensor
includes a deformable membrane portion, a first sensing element, and a second sensing element.
The first sensing element is fixed to the film portion, and is provided between a first magnetic
layer of a first material, a first opposing magnetic layer, and the first magnetic layer and the first
opposing magnetic layer. And a first intermediate layer. The second sensing element is fixed to
the film portion, and a second magnetic layer of a second material different from the first
material, a second opposing magnetic layer, the second magnetic layer, and the second opposing
magnetic layer And a second intermediate layer provided therebetween. [Selected figure] Figure
1
Sensor, information terminal, microphone, blood pressure sensor and touch panel
[0001]
Embodiments of the present invention relate to a pressure sensor, a microphone, a blood
pressure sensor and a touch panel.
[0002]
A pressure sensor using a magnetic layer has been proposed.
The pressure sensor is applied to, for example, a microphone, a blood pressure sensor, a touch
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panel, and the like. In pressure sensors, a wide dynamic range is desired.
[0003]
JP, 2015-61056, A
[0004]
Embodiments of the present invention provide a pressure sensor, a microphone, a blood pressure
sensor, and a touch panel capable of expanding a dynamic range.
[0005]
According to an embodiment of the invention, the pressure sensor comprises a deformable
membrane part, a first sensing element and a second sensing element.
The first sensing element is fixed to the film portion, and is provided between a first magnetic
layer of a first material, a first opposing magnetic layer, and the first magnetic layer and the first
opposing magnetic layer. And a first intermediate layer.
The second sensing element is fixed to the film portion, and a second magnetic layer of a second
material different from the first material, a second opposing magnetic layer, the second magnetic
layer, and the second opposing magnetic layer And a second intermediate layer provided
therebetween.
[0006]
FIG. 1A to FIG. 1D are schematic views illustrating the pressure sensor according to the first
embodiment. FIG. 2A to FIG. 2D are schematic views illustrating the pressure sensor according to
the first embodiment. FIG. 3A and FIG. 3B are schematic views illustrating the pressure sensor
according to the first embodiment. FIG. 4A and FIG. 4D are graphs illustrating the characteristics
of the pressure sensor according to the first embodiment. It is a schematic plan view which
illustrates the pressure sensor concerning a 2nd embodiment. FIG. 6A to FIG. 6D are schematic
perspective views illustrating the pressure sensor according to the second embodiment. FIGS. 7A
and 7B are schematic perspective views illustrating a portion of another pressure sensor
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according to the second embodiment. It is a schematic perspective view which illustrates a part
of pressure sensor concerning an embodiment. It is a schematic perspective view which
illustrates a part of another pressure sensor which concerns on embodiment. It is a schematic
perspective view which illustrates a part of another pressure sensor which concerns on
embodiment. It is a schematic perspective view which illustrates a part of another pressure
sensor which concerns on embodiment. It is a schematic perspective view which illustrates a part
of another pressure sensor which concerns on embodiment. It is a schematic perspective view
which illustrates a part of another pressure sensor which concerns on embodiment. It is a
schematic perspective view which illustrates a part of another pressure sensor which concerns
on embodiment. It is a schematic diagram which illustrates the microphone concerning a 3rd
embodiment. It is a schematic cross section which illustrates another microphone concerning a
3rd embodiment. FIGS. 17A and 17B are schematic views illustrating the blood pressure sensor
according to the fourth embodiment. It is a schematic diagram which illustrates the touch panel
concerning a 5th embodiment. It is a schematic plan view which illustrates a pressure sensor.
[0007]
Hereinafter, embodiments of the present invention will be described with reference to the
drawings. The drawings are schematic or conceptual, and the relationship between the thickness
and width of each part, the ratio of sizes between parts, and the like are not necessarily the same
as the actual ones. Even in the case of representing the same part, the dimensions and
proportions may differ from one another depending on the drawings. In the specification of the
present application and the drawings, the same elements as those described above with reference
to the drawings are denoted by the same reference numerals, and the detailed description will be
appropriately omitted.
[0008]
First Embodiment FIGS. 1A to 1D are schematic views illustrating a pressure sensor according to
a first embodiment. FIG. 1A is a perspective view. FIG. 1B is a cross-sectional view taken along
line A <b> 1-A <b> 2 of FIG. FIG.1 (c) is the top view seen from arrow AR of FIG. 1 (a). FIG. 1D is a
cross-sectional view illustrating a part of the pressure sensor.
[0009]
As shown in FIG. 1A, the pressure sensor 110 according to the embodiment includes a film unit
70d, a first sensing element 51, and a second sensing element 52.
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[0010]
The film part 70d is deformable.
The first detection element 51 is fixed to the film unit 70d. The second detection element 52 is
fixed to the film unit 70d. In this example, the first detection element 51 is fixed to a first
position (first region) of the film unit 70d. The second detection element 52 is fixed to a second
position (second region) of the film unit 70d.
[0011]
The first detection element 51 is provided on part of the film unit 70d. The second detection
element 52 is provided on another part of the film unit 70d.
[0012]
The direction from the film unit 70 d toward the first detection element 51 is taken as the Z-axis
direction. One direction perpendicular to the Z-axis direction is taken as the X-axis direction. A
direction perpendicular to the Z-axis direction and the X-axis direction is taken as a Y-axis
direction.
[0013]
In this example, a plurality of first sensing elements 51 and a plurality of second sensing
elements 52 are provided. In this example, the plurality of first detection elements 51 are
arranged along the X-axis direction. In this example, the plurality of second detection elements
52 are arranged along the X-axis direction. For example, the second detection element 52 is
aligned with the first detection element in the Y-axis direction. For example, the plurality of first
sensing elements 51 are connected in series to one another. For example, the plurality of second
sensing elements 52 are connected in series with one another. In the embodiment, the number of
first sensing elements 51 is arbitrary. The number of second detection elements 52 is arbitrary.
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[0014]
The film unit 70d is held by the holding unit 70s. The film portion 70d has an outer edge 70r.
The holding portion 70s holds the outer edge 70r. For example, a substrate to be the film unit 70
d and the holding unit 70 s is provided. The substrate is, for example, a silicon substrate. A part
of the substrate is removed, and a cavity 70h is provided in the substrate (see FIG. 1 (b)). The thin
part of the substrate becomes the film part 70d. The thick portion of the substrate serves as the
holding portion 70s.
[0015]
As shown in FIG. 1B, the first sensing element 51 includes a first magnetic layer 11a of a first
material, a first opposing magnetic layer 11b, and a first intermediate layer 11c. The first
intermediate layer 11c is provided between the first magnetic layer 11a and the first opposing
magnetic layer 11b. The first opposing magnetic layer 11b is separated from the first magnetic
layer 11a substantially along the Z-axis direction. In this example, the first opposing magnetic
layer 11b is provided between the first magnetic layer 11a and the film portion 70d. In the
embodiment, the first magnetic layer 11a may be disposed between the first opposing magnetic
layer 11b and the film portion 70d.
[0016]
The second sensing element 52 includes a second magnetic layer 12 a of a second material, a
second opposing magnetic layer 12 b, and a second intermediate layer 12 c. The second
intermediate layer 12c is provided between the second magnetic layer 12a and the second
opposing magnetic layer 12b. The second opposing magnetic layer 12 b is separated from the
second magnetic layer 12 a substantially along the Z-axis direction. In this example, the second
opposing magnetic layer 12b is provided between the second magnetic layer 12a and the film
portion 70d. In the embodiment, the second magnetic layer 12a may be disposed between the
second opposing magnetic layer 12b and the film portion 70d.
[0017]
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The magnetization (first magnetization) of the first magnetic layer 11a changes according to the
deformation of the film portion 70d. The magnetization (second magnetization) of the second
magnetic layer 12a changes in accordance with the deformation of the film portion 70d. The first
magnetic layer 11a is, for example, a magnetization free layer. The second magnetic layer 12a is,
for example, a magnetization free layer.
[0018]
For example, the magnetization of the first opposing magnetic layer 11b is less likely to change
than the first magnetization of the first magnetic layer 11a. The first opposing magnetic layer 11
b is, for example, a magnetization fixed layer (for example, a reference layer). For example, the
magnetization of the second opposing magnetic layer 12b is less likely to change than the second
magnetization of the second magnetic layer 12a. The second opposing magnetic layer 12 b is, for
example, a magnetization fixed layer (for example, a reference layer).
[0019]
For example, pressure (pressure to be detected) is applied to the film part 70d. This causes
distortion in the magnetic layer of the sensing element. The strain is, for example, an anisotropic
strain. Due to this strain, each of the first magnetization of the first magnetic layer 11a and the
second magnetization of the second magnetic layer 12a changes. This change is based on, for
example, the inverse magnetostrictive effect. Thus, the angle between the direction of the first
magnetization of the first magnetic layer 11a and the direction of the magnetization of the first
opposing magnetic layer 11b changes. Thereby, the resistance between the first magnetic layer
11a and the first opposing magnetic layer 11b changes. On the other hand, the angle between
the direction of the second magnetization of the second magnetic layer 12a and the direction of
the magnetization of the second opposing magnetic layer 12b changes. Thereby, the resistance
between the second magnetic layer 12a and the second opposing magnetic layer 12b changes.
These changes in resistance are based on, for example, the magnetoresistive effect (MR effect).
[0020]
That is, the resistance between the first magnetic layer 11a and the first opposing magnetic layer
11b changes in accordance with the deformation of the film portion 70d. The angle between the
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direction of the second magnetization of the second magnetic layer 12a and the direction of the
magnetization of the second opposing magnetic layer 12b changes. By detecting these changes in
resistance, the pressure applied to the film portion 70d is detected. That is, the pressure to be
detected is detected.
[0021]
In the embodiment, the magnetization of the first opposing magnetic layer 11b may change
according to the deformation of the film portion 70d. Also at this time, the angle between the
direction of the first magnetization of the first magnetic layer 11a and the direction of the
magnetization of the first opposing magnetic layer 11b changes. In the embodiment, the
magnetization of the second opposing magnetic layer 12b may change according to the
deformation of the film portion 70d. Also at this time, the angle between the direction of the
second magnetization of the second magnetic layer 12a and the direction of the magnetization of
the second opposing magnetic layer 12b changes.
[0022]
The change in resistance is detected, for example, by applying a current to the detection element.
[0023]
As illustrated in FIG. 1B, for example, a first electrode 58a and a second electrode 58b are
provided.
For example, the first magnetic layer 11a, the first opposing magnetic layer 11b, and the first
intermediate layer 11c are disposed between the first electrode 58a and the second electrode
58b. By applying a voltage between the first electrode 58a and the second electrode 58b, the
resistance of the first detection element 51 is detected.
[0024]
As illustrated in FIG. 1D, for example, a third electrode 58c and a fourth electrode 58d are
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provided. For example, the second magnetic layer 12a, the second opposing magnetic layer 12b,
and the second intermediate layer 12c are disposed between the third electrode 58c and the
fourth electrode 58d. By applying a voltage between the third electrode 58c and the fourth
electrode 58d, the resistance of the second detection element 52 is detected.
[0025]
As illustrated in FIG. 1B, in this example, an insulating layer 58i is provided between the first
electrode 58a and the film portion 70d. The insulating layer 58i is also provided, for example,
between the first electrode 58a and the second electrode 58b. The insulating layer 58i is
provided, for example, also between the third electrode 58c and the fourth electrode 58d. The
insulating layer 58i provides electrical insulation between the electrodes.
[0026]
As shown in FIG. 1C, the pressure sensor 110 may further include a processing unit 68 (for
example, a processing circuit). The processing unit 68 is electrically connected to the first
detection element 51 and the second detection element 52. For example, the processing unit 68
is electrically connected to the first electrode 58a, the second electrode 58b, the third electrode
58c, and the fourth electrode 58d. The processing unit 68 outputs a signal corresponding to the
signal obtained from the first detection element 51 (the signal generated by the first detection
element 51). The processing unit 68 outputs a signal corresponding to the signal obtained from
the second detection element 52 (the signal generated by the second detection element 52). The
processing unit 68 outputs a signal corresponding to a change in resistance generated in the
sensing element. The signal obtained by the processing unit 68 corresponds to the pressure to be
detected.
[0027]
As shown in FIG. 1C, in this example, the film portion 70d (outer edge 70r) is substantially
polygonal (square, specifically rectangular). The outer edge 70r of the film portion 70d includes
a first side 70s1, a second side 70s2, a third side 70s3, and a fourth side 70s4.
[0028]
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Various shapes can be applied to the film portion 70d (the outer edge 70r). The film portion 70d
(the outer edge 70r) may be, for example, a substantially circular shape, a flat circular shape
(including an elliptical shape), a substantially square shape, or a rectangular shape. For example,
when the film portion 70d (the outer edge 70r) has a substantially square shape or a
substantially rectangular shape, the four corner portions (corner portions) may have a curved
shape.
[0029]
The first side 70s1 extends in a first direction (in this example, the X-axis direction). The second
side 70s2 is separated from the first side 70s1 in the second direction. The second direction
intersects the first direction. In this example, the second direction is the Y-axis direction. The
second side 70s1 extends in the first direction (X-axis direction). The third side 70s3 extends in
the second direction (Y-axis direction). The fourth side 70s4 is separated from the third side
70s3 in the first direction (X-axis direction), and extends in the second direction (Y-axis
direction).
[0030]
In this example, the distance along the first direction between the third side 70s3 and the fourth
side 70s4 is longer than the distance along the second direction between the first side 70s1 and
the second side 70s2. The film portion 70d is substantially rectangular, and the first side 70s1
and the second side 70s2 are long sides. The third side 70s3 and the fourth side 70s4 are short
sides.
[0031]
As illustrated in FIG. 1C, in the embodiment, a curved portion may be provided between the side
at the outer edge 70r. For example, the corner portion of the film portion 70d (the outer edge
70r) is curved. Thereby, for example, the strength of the film unit 70d is improved.
[0032]
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When stress is applied to the film portion 70d, a large strain (anisotropic strain) occurs in the
vicinity of the outer edge 70r of the film portion 70d. By arranging the sensing element in the
vicinity of the outer edge 70r of the film portion 70d, a large strain is added to the sensing
element, and high sensitivity can be obtained. In particular, when the length of one of the film
portions 70d is longer than the length in the other direction (that is, when the shape is
anisotropic), particularly large distortion occurs in a portion along the major axis of the outer
edge 70r. It occurs. For this reason, particularly high sensitivity can be obtained by arranging the
sensing element in a portion along the long side of the outer edge 70r.
[0033]
In this example, the plurality of first detection elements 51 are arranged along the first side
70s1. The plurality of second detection elements 52 are arranged along the second side 70s2.
When one of the lengths of the film portion 70d is longer than the other length of the film
portion 70d (when the shape is anisotropic), the film portion 70d is compared with when the film
portion 70d has an isotropic shape. The area in which anisotropic distortion occurs near the end
on the short axis side of is wide.
[0034]
An anisotropic strain with a large absolute value occurs in a wide region at the end on the short
axis side of the film portion 70d having the anisotropic shape than the end of the film portion
70d having the isotropic shape. In the film part 70d having an anisotropic shape, more detection
elements can be arranged than the film part 70d having an isotropic shape. The sensing element
to be placed is a sensing element that produces a similar (e.g., same polarity) change in electrical
resistance with pressure. Thereby, a highly sensitive pressure sensor can be provided.
[0035]
The SN ratio can be improved by connecting a plurality of sensing elements in series. In
embodiments, multiple sensing elements can be arranged that provide an electrical signal of the
same polarity when pressure is applied. This improves the SN ratio.
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[0036]
In the embodiment, the number N of sensing elements connected in series and the bias voltage
are set to, for example, an appropriate voltage range. For example, it is preferable that the
voltage when a plurality of sensing elements are electrically connected in series is 1 V or more
and 10 V or less. For example, when the bias voltage applied to one sensing element is 50 mV,
the number N of sensing elements connected in series is preferably 20 or more and 200 or less.
When the bias voltage applied to one sensing element is 150 mV, the number N of sensing
elements connected in series is preferably 7 or more and 66 or less.
[0037]
In the embodiment, the second material of the second magnetic layer 12a is different from the
first material of the first magnetic layer 11a. Thus, the sensitivity of the second sensing element
52 including the second magnetic layer 12a is different from the sensitivity of the first sensing
element 51 including the first magnetic layer 11a. The sensitivity is a gauge factor described
later.
[0038]
For example, the composition of the second magnetic layer 12a is different from the composition
of the first magnetic layer 11a. For example, the first magnetic layer 11a contains at least one of
Fe, Co, and Ni at a first concentration. The second magnetic layer 12a contains at least one of Fe,
Co, and N1 described above at a second concentration. The second concentration is different
from the first concentration.
[0039]
For example, the concentration (composition ratio) of Fe in the second magnetic layer 11a is
different from the concentration (composition ratio) of Fe in the first magnetic layer 11a. For
example, the concentration (composition ratio) of Co in the second magnetic layer 11a is
different from the concentration (composition ratio) of Co in the first magnetic layer 11a. For
example, the concentration (composition ratio) of Ni in the second magnetic layer 11a is different
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from the concentration (composition ratio) of Ni in the first magnetic layer 11a.
[0040]
For example, the first magnetic layer 11a contains Fe, and the second magnetic layer 12a
contains Fe. At this time, the concentration (composition ratio) of Fe in the second magnetic layer
12a is different from the concentration (composition ratio) of Fe in the first magnetic layer 11a.
For example, the composition ratio of Fe in the first magnetic layer 11a is 60 at. % (Atomic
percent) or more and 100 at. % Or less. For example, the composition ratio of Fe in the second
magnetic layer 11a is 0 at. % Or more 60 at. Less than%.
[0041]
For example, the concentration of B (boron) may be different between the first magnetic layer
11a and the second magnetic layer 12a. Thereby, the sensitivity of the second detection element
52 is different from the sensitivity of the first detection element 51. For example, the
composition ratio of B in the first magnetic layer 11a is 10 at. % To 30 at. % Or less. For example,
the composition ratio of B in the second magnetic layer 11a is 0 at. % Or more and 10 at. Less
than%.
[0042]
For example, the first magnetic layer 11 a includes B and at least one of Fe, Co, and Ni. The
second magnetic layer 12 a contains at least one of Fe, Co, and N1 and does not contain B. At this
time, the sensitivity of the second detection element 52 is lower than the sensitivity of the first
detection element 51.
[0043]
For example, the first magnetic layer 11 a includes B and at least one of Fe, Co, and Ni. The
second magnetic layer 12 a includes B, at least one of Fe, Co, and N1. The concentration
(composition ratio) of B contained in the second magnetic layer 12a is lower than the
concentration (composition ratio) of B contained in the first magnetic layer 11a. For example, the
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composition ratio of Fe in the first magnetic layer 11a is 60 at. % (Atomic percent) or more and
100 at. % Or less. For example, the composition ratio of Fe in the second magnetic layer 11a is 0
at. % Or more 60 at. Less than%. For example, the composition ratio of B in the first magnetic
layer 11a is 10 at. % To 30 at. % Or less. For example, the composition ratio of B in the second
magnetic layer 11a is 0 at. % Or more and 10 at. Less than%. At this time, the sensitivity of the
second detection element 52 is lower than the sensitivity of the first detection element 51.
[0044]
For example, the first magnetic layer 11 a contains Co 40 Fe 40 B 20. For example, the second
magnetic layer 12 a contains Co 50 Fe 50.
[0045]
For example, the first magnetic layer 11 a contains Fe 80 B 20. For example, the second
magnetic layer 12 a contains Co 40 Fe 40 B 20.
[0046]
The composition in these magnetic layers can be determined, for example, by a combination
analysis technique of cross-sectional TEM (Transmission Electron Microscope) and EDX (Energy
Dispersive X-ray Spectroscopy). The composition in these magnetic layers can be determined, for
example, by a cross-sectional TEM and an analysis method of a combination of electron energyloss spectroscopy (EELS). The composition in these magnetic layers can be determined, for
example, by an analysis method such as SIMS (Secondary Ion Mass Spectrometry).
[0047]
For example, the crystallinity may be different between the first magnetic layer 11a and the
second magnetic layer 12a. For example, the first magnetic layer 11a includes an amorphous
region. The second magnetic layer 12a includes a crystalline region. For example, the second
magnetic layer 12a does not include an amorphous region. For example, the amount of the
amorphous region in the second magnetic layer 11a (for example, the width of the amorphous
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region per unit cross-sectional area) is the amount of the amorphous region in the first magnetic
layer 11a (for example, the width of the amorphous region per unit cross-sectional area Less
than that). For example, the first magnetic layer 11a may not substantially include the crystalline
region.
[0048]
The crystallinity in these magnetic layers is determined by an analysis method such as a crosssectional TEM (Transmission Electron Microscope).
[0049]
Hereinafter, examples of the first magnetic layer 11 a used for the first sensing element 51 and
the second magnetic layer 12 a used for the second sensing element 52 will be described.
[0050]
FIG. 2A to FIG. 2D are schematic views illustrating the pressure sensor according to the first
embodiment.
2 (a) and 2 (b) correspond to the first configuration S01.
FIG.2 (c) and FIG.2 (d) respond ¦ correspond to 2nd structure S02.
[0051]
FIGS. 2 (a) and 2 (c) show examples of the depth profiles of the elements of the sample by
electron energy loss spectroscopy (EELS). In these figures, the horizontal axis is the intensity Int
(arbitrary unit) of detection of the element. The vertical axis is the depth Dp (nm). The depth Dp
corresponds to, for example, a distance in the Z-axis direction. In FIGS. 2 (a) and 2 (c), depth
profiles for iron, boron and oxygen are shown. FIG.2 (b) and FIG.2 (d) are the cross-sectional
transmission electron microscope (cross-sectional TEM) photograph image of a sample.
[0052]
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The sample of the first configuration S01 has the following configuration. A pinning layer (Ir 22
Mn 78, 7 nm)) is provided on the underlayer ((Ta, 1 nm) / (Ru, 2 nm)). A magnetization fixed
layer (Co75Fe25, 2.5 nm) is provided thereon. A magnetic coupling layer (Ru, 0.9 nm) is
provided thereon. A magnetization fixed layer (Co40Fe40B20, 3 nm) is provided thereon. An
intermediate layer (Mg-O, 1.6 nm) is provided thereon. A magnetic layer (Co40Fe40B20, 4 nm) is
provided thereon. A functional layer (Mg-O, 1.5 nm) is provided thereon. A cap layer ((Cu, 1 nm)
/ (Ta, 20 nm) / Ru, 50 nm) is provided thereon.
[0053]
The magnetic layer (Co 40 Fe 40 B 20, 4 nm) corresponds to the first magnetic layer 11 a. The
middle layer corresponds to the first middle layer 11c. The magnetization fixed layer (Co 40 Fe
40 B 20, 3 nm) corresponds to the first opposing magnetic layer 11 b.
[0054]
On the other hand, in the sample of the second configuration S02, no functional layer is provided
with respect to the sample of the first configuration S01 described above. The magnetic layer (Co
40 Fe 40 B 20, 4 nm) corresponds to the second magnetic layer 12 a. The middle layer
corresponds to the second middle layer 12c. The magnetization fixed layer (Co 40 Fe 40 B 20, 3
nm) corresponds to the second opposing magnetic layer 12 b.
[0055]
As can be seen from FIG. 2A, in the first configuration S01, the concentration of boron is high in
the first magnetic layer 11a (Co-Fe-B layer). As can be seen from FIG. 2C, in the second
configuration S02, the concentration of boron is low in the second magnetic layer 12a (Co-Fe-B
layer). It is considered that boron diffuses to the cap layer side and the concentration of boron in
the second magnetic layer 12a is reduced.
[0056]
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The crystallization in the Co 40 Fe 40 B 20 layer of the second configuration S 02 in which the
functional layer is not provided proceeds more than the Co 40 Fe 40 B 20 layer of the first
configuration S 01. In the first configuration S01, the Co 40 Fe 40 B 20 layer has an amorphous
structure. In the second configuration S02 in which the functional layer is not provided,
crystallization proceeds. In the second configuration S02, it is considered that the boron is
diffused and the boron content in the second magnetic layer 12a is reduced.
[0057]
Thus, the concentration (composition ratio) of B contained in the second magnetic layer 12a is
lower than the concentration (composition ratio) of B contained in the first magnetic layer 11a.
Alternatively, the second magnetic layer 12 a does not contain B.
[0058]
FIG. 3A and FIG. 3B are schematic views illustrating the pressure sensor according to the first
embodiment. These figures are graphs illustrating the characteristics of the sensing element. FIG.
3 (a) corresponds to the first configuration S01, and FIG. 3 (b) corresponds to the second
configuration S02. These figures show the electrical resistance R in the sensing element when the
strain ε is changed. The strain ε is continuously changed in the range between −0.8 × 10 3 <3> and 0.8 × 10 3 <-3>. The horizontal axis is strain ε. The vertical axis is the electrical
resistance R. The change in strain ε is from -0.8 × 10 <-3> to 0.8 × 10 <-3> and 0.8 × 10 <-3>
to -0.8 × 10 < -3> Both are changes towards>. The gauge factor is calculated from these figures.
[0059]
The gauge factor GF is represented by GF = (dR / R) / dε. The gauge factor in the first
configuration S01 is calculated as 4027. The gauge factor in the second configuration S02 is
calculated as 895.
[0060]
Thus, in the first configuration S01 and the second configuration S02, the concentrations of B are
different from each other, resulting in different gauge factors.
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[0061]
In the embodiment, for example, the first configuration S01 described above is applied as the
first magnetic layer 11a of the first sensing element 51.
On the other hand, for example, the second configuration S02 described above is applied as the
second magnetic layer 12a of the second sensing element 52. Thereby, the gauge factor of the
second sensing element 52 is changed from the gauge factor of the first sensing element 51.
[0062]
FIG. 4A and FIG. 4D are graphs illustrating the characteristics of the pressure sensor according to
the first embodiment. 4A and 4B correspond to the first detection element 51. FIG. FIGS. 4C and
4D correspond to the second detection element 52. FIG. In FIG. 4A and FIG. 4C, the horizontal
axis is the pressure Ps, and the vertical axis is the strain ε. In FIG. 4B and FIG. 4D, the horizontal
axis is the electrical resistance R, and the vertical axis is the strain ε.
[0063]
As shown in FIGS. 4A and 4B, when a small pressure Ps is applied to the first sensing element 51
having a high gauge factor, the electrical resistance R changes in accordance with the pressure
Ps. Because of the high gauge factor, the sensitivity of the electrical resistance R to the pressure
Ps is high. When a large pressure Ps is applied to the first sensing element 51, the electrical
resistance R is in a saturated state, and a change in the electrical resistance R according to the
pressure Ps can not be obtained.
[0064]
On the other hand, as shown in FIGS. 4C and 4D, in the second sensing element 52 having a low
gauge factor, the electrical resistance R changes according to the pressure Ps even if a large
pressure Ps is applied. . When a small pressure Ps is applied, the sensitivity of the electrical
04-05-2019
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resistance R to the pressure Ps is lower than that of the first sensing element 51.
[0065]
In the embodiment, such first sensing element 51 and second sensing element 52 are used.
Thereby, for example, a small pressure is detected using the first detection element 51. High
pressure is detected using the second sensing element 52. Thereby, small pressure and large
pressure can be detected. That is, a pressure sensor capable of expanding the dynamic range can
be provided. The sensitivity at the time of detecting a smaller pressure on the first detection
element 51 is high. That is, high sensitivity and wide dynamic range can be obtained.
[0066]
For example, pressure sensor 110 is applied to a microphone. For example, a small sound is
detected by the first detection element 51, and a large sound is detected by the second detection
element 52. Sound can be detected with high sensitivity and wide dynamic range.
[0067]
The strain (anisotropic strain) generated when pressure is applied differs at the in-plane position
of the film portion 70d. The first detection element 51 and the second detection element 52 may
be disposed in the region where the same distortion occurs in the film unit 70d. In the
embodiment, the gauge factors of the first sensing element 51 and the second sensing element
52 are different from each other. For this reason, even when the detection elements are arranged
in the region where the same distortion occurs in the film portion 70d, the change in the
obtained electrical resistance R is different.
[0068]
In the embodiment, these sensing elements 51 may be arranged in a region where large
distortion can be obtained. This enables high sensitivity detection.
04-05-2019
18
[0069]
For example, the first detection element 51 is closest to the first portion of the outer edge 70r of
the film portion 70d. The first portion is, for example, a first side 70s1. The second sensing
element 52 is closest to the second portion of the outer edge 70r. The second portion is a second
side 70s2. The first spacing between the first sensing element 51 and the first portion is
substantially equal to the second spacing between the second sensing element 52 and the second
portion. The difference between the first interval and the second interval is, for example, 0.2
times or less of the first interval.
[0070]
As described above, a large strain (anisotropic strain) is obtained in the vicinity of the outer edge
70r of the film portion 70d. By arranging the sensing element in the area near the outer edge
70r, high sensitivity can be obtained. And, even if sensing elements having different gauge
factors are arranged in the same area, a wide dynamic range can be obtained.
[0071]
For example, these sensing elements may be stacked. For example, at least a part of the second
detection element 52 may overlap the first detection element 51 along the direction (Z-axis
direction) from the film unit 70 d toward the first detection element 51. Also in this case, a wide
dynamic range can be obtained.
[0072]
In the embodiment, for example, any one of the signal obtained by the first detection element 51
and the signal obtained by the second detection element 52 may be output as a detection signal.
The selection of this signal is performed by the processing unit 68, for example. That is, the
pressure sensor 110 further includes a processing unit 68 connected to the first sensing element
51 and the second sensing element 52. The processing unit 68 outputs a first output signal
according to the first signal obtained from the first detection element 51, and a second output
signal according to the second signal obtained from the second detection element 52. And the
second operation of outputting.
04-05-2019
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[0073]
For example, the processing unit 68 performs the above-described first operation when the first
amplitude of the first signal is larger than the second amplitude of the second signal. The second
operation is performed when the second amplitude is greater than the first amplitude.
[0074]
For example, the processing unit 68 performs the first operation described above when the first
amplitude of the first signal is equal to or less than the threshold. The second operation is
performed when the first amplitude exceeds the threshold.
[0075]
As described above, the pressure sensor 110 includes the deformable film unit 70 d, the first
detection element 51, the second detection element 52, and the processing unit. The first sensing
element 51 is fixed to the film portion 70d, and is provided between the first magnetic layer 11a,
the first opposing magnetic layer 11b, and the first magnetic layer 11a and the first opposing
magnetic layer 11b. And an intermediate layer 11c. The second sensing element 52 is fixed to
the film portion 70d, and is provided between the second magnetic layer 12a, the second
opposing magnetic layer 12b, and the second magnetic layer 12a and the second opposing
magnetic layer 12b. And an intermediate layer 12c. The processing unit 68 is connected to the
first detection element 51 and the second detection element 52. The processing unit 68 outputs
a first output signal according to the first signal obtained from the first detection element 51, and
a second output signal according to the second signal obtained from the second detection
element 52. And the second operation of outputting.
[0076]
The operation of the processing unit 68 can provide a pressure sensor capable of expanding the
dynamic range.
[0077]
04-05-2019
20
Second Embodiment FIG. 5 is a schematic plan view illustrating a pressure sensor according to a
second embodiment.
As shown in FIG. 5, the pressure sensor 120 according to the present embodiment includes a film
unit 70 d, a first sensing element 51, a second sensing element 52, a third magnetic layer 43, and
a fourth magnetic layer 44. including. The film part 70d is deformable. The first detection
element 51 is fixed to the film unit 70d. The first sensing element 51 includes a first magnetic
layer 11a, a first opposing magnetic layer 11b, and a first intermediate layer 11c provided
between the first magnetic layer 11a and the first opposing magnetic layer 11b. (Refer to FIG. 1
(b)). The second detection element 52 is fixed to the film unit 70d. The second sensing element
52 includes a second magnetic layer 12a, a second opposing magnetic layer 12b, and a second
intermediate layer 12c provided between the second magnetic layer 12a and the second
opposing magnetic layer 12b. (See FIG. 1 (d)).
[0078]
The third magnetic layer 43 is made of a first alloy containing Co and Pt, a second alloy
containing Fe and Pt, a third alloy containing Co and Pd, and a fourth alloy containing Fe and Pd.
At least one selected from the group.
[0079]
The fourth magnetic layer 44 is made of a sixth alloy containing Co and Pt, a seventh alloy
containing Fe and Pt, an eighth alloy containing Co and Pd, and a ninth alloy containing Fe and
Pd. At least one selected from the group.
[0080]
In this example, a plurality of third magnetic layers 43 (magnetic layers 43a and 43b) are
provided.
The first sensing element 51 is disposed between these magnetic layers.
[0081]
04-05-2019
21
In this example, a plurality of fourth magnetic layers 44 (magnetic layer 44 a and magnetic layer
44 b) are provided.
The second sensing element 52 is disposed between these magnetic layers.
[0082]
In the pressure sensor 120, the configuration described in regard to the first embodiment can be
applied to the film unit 70d, the first detection element 51, and the second detection element 52.
However, in the second embodiment, the material or the like of the first sensing element 51 may
be the same as or different from the material or the like of the second sensing element 52. In the
pressure sensor 120, a processing unit 68 may be provided. Hereinafter, the pressure sensor
120 will be described in terms of portions different from the pressure sensor 110.
[0083]
In the second embodiment, with the third magnetic layer 43 and the fourth magnetic layer 44,
the characteristics (for example, gauge factor) of the first sensing element 51, the characteristics
(for example, gauge factor) of the second sensing element 52, and the other It is different.
[0084]
For example, the third magnetic layer 43 applies a magnetic field bias to the first sensing
element 51.
The fourth magnetic layer 44 applies a magnetic field bias to the second sensing element 52.
These magnetization biases are different from each other.
[0085]
The third magnetic layer 43 is disposed close to the first magnetic layer 11a. The fourth
04-05-2019
22
magnetic layer 44 is disposed close to the second magnetic layer 12a. For example, the first
distance d1 between the first magnetic layer 11a and the third magnetic layer 43 is shorter than
the distance d3 between the first magnetic layer 11a and the fourth magnetic layer 44. The
second distance d 2 between the second magnetic layer 12 a and the fourth magnetic layer 44 is
shorter than the distance d 4 between the second magnetic layer 12 a and the third magnetic
layer 43.
[0086]
At this time, between the third magnetic layer 43 and the fourth magnetic layer 44, at least a
layer thickness, a layer length, a layer width, a distance between the magnetization free layer, a
composition, and at least a magnetization direction. One is different.
[0087]
FIG. 6A to FIG. 6D are schematic perspective views illustrating the pressure sensor according to
the second embodiment.
In the example shown in FIG. 6A, the third magnetic layer 43 is aligned with the first sensing
element 51 (the first magnetic layer 11a) in the direction intersecting the Z-axis direction. In the
example shown in FIG. 6B, the fourth magnetic layer 44 is aligned with the second detection
element 52 (second magnetic layer 12a) in the direction intersecting the Z-axis direction.
[0088]
As shown in FIG. 6A, for example, the third magnetic layer 43 has a first length L1, a second
length L2, a third length L3, a first distance d1, and a third magnetization direction 43M. Have.
Furthermore, the third magnetic layer 43 has a first composition. The first length L1 is a length
(thickness) of the third magnetic layer 43 along the first direction. The first direction
corresponds to the Z-axis direction from the film unit 70 d toward the first detection element 51.
The second length L2 is a length of the third magnetic layer 43 along the second direction. The
second direction is perpendicular to the first direction. In this example, the second direction is
the X-axis direction. The third length L3 is a length (width) of the third magnetic layer 43 in the
third direction. The third direction is perpendicular to the first direction and perpendicular to the
second direction. The first distance d1 is a distance between the first magnetic layer 11a and the
third magnetic layer 43. The third magnetization direction 43M is the direction of the
04-05-2019
23
magnetization of the third magnetic layer 43.
[0089]
As shown in FIG. 6B, for example, the fourth magnetic layer 44 has a fourth length L4, a fifth
length L5, a sixth length L6, a second distance d2, and a fourth magnetization direction 44M.
Have. Furthermore, the fourth magnetic layer 44 has a second composition. The fourth length L4
is a length (thickness) of the fourth magnetic layer 44 along the first direction. The fifth length
L5 is a length of the fourth magnetic layer 44 in the second direction. The sixth length L6 is a
length (width) of the fourth magnetic layer 44 in the third direction. The second distance d 2 is a
distance between the second magnetic layer 12 a and the fourth magnetic layer 44. The fourth
magnetization direction 44 M is the direction of the magnetization of the fourth magnetic layer
44.
[0090]
As shown in FIGS. 6A and 6B, the fourth length L4 is different from the first length L1. The fifth
length L5 is different from the second length L2. The sixth length L6 is different from the third
length L3. The second distance d2 is different from the first distance d1. The fourth
magnetization direction 44M is different from the third magnetization direction 43M.
Furthermore, the second composition of the fourth magnetic layer 44 may be different from the
first composition of the third magnetic layer 43.
[0091]
In the example shown in FIG. 6C, at least a part of the third magnetic layer 43 is aligned with the
first sensing element 51 (first magnetic layer 11a) in the Z-axis direction. In the example shown
in FIG. 6D, at least a part of the fourth magnetic layer 44 is aligned with the second sensing
element 52 (second magnetic layer 12a) in the Z-axis direction.
[0092]
As shown in FIGS. 6C and 6D, the fourth length L4 is different from the first length L1. The fifth
04-05-2019
24
length L5 is different from the second length L2. The sixth length L6 is different from the third
length L3. The second distance d2 is different from the first distance d1. The fourth
magnetization direction 44M is different from the third magnetization direction 43M.
Furthermore, the second composition of the fourth magnetic layer 44 may be different from the
first composition of the third magnetic layer 43.
[0093]
Thus, in the present embodiment, the fourth magnetic layer 44 has a fourth length L4 different
from the first length L1 and a fifth length L5 different from the second length L2 and a third
length L3. Is at least one of a sixth length L6 different from each other, a second distance d2
different from the first distance d1, a second composition different from the first composition,
and a fourth magnetization direction 44M different from the third magnetization direction 43M.
Have.
[0094]
Thereby, the characteristic (for example, gauge factor) in the second sensing element 52 is
different from the characteristic (for example, gauge factor) in the first sensing element 51.
For example, the gauge factor at the second sensing element 52 is lower than the gauge factor at
the first sensing element 51.
[0095]
By using such a plurality of sensing elements, it is possible to provide a pressure sensor capable
of expanding the dynamic range.
[0096]
In the pressure sensor 120, for example, Co̶Pt, Fe̶Pt, Co̶Pd, or Fe̶Pd is used for at least
one of the third magnetic layer 43 and the fourth magnetic layer 44.
In these materials, magnetic anisotropy and coercivity are relatively high. These materials are, for
example, hard magnetic materials (hard ferromagnetic materials).
04-05-2019
25
[0097]
At least one of the third magnetic layer 43 and the fourth magnetic layer 44 may contain Co̶Pt,
Fe̶Pt, Co̶Pd, or an alloy obtained by adding an additional element to Fe̶Pd.
[0098]
For example, at least one of the third magnetic layer 43 and the fourth magnetic layer 44 is made
of CoPt (the ratio of Co is 50 at.
% Or more and 85 at. % Or less), (CoxPt100-x) 100-yCry (x is 50 at. % Or more and 85 at. % Or
less, y is 0 at. % Or more 40 at. % Or less) or FePt (the ratio of Pt is 40 at. % Or more 60 at. % Or
less).
[0099]
For example, in the third magnetic layer 43, Fe̶Pt (Fe ratio is 30 at. % To 70 at. % Or less). The
fourth magnetic layer 44 is made of CoPt (the ratio of Co is 50 at. % Or more and 85 at. % Or
less). At this time, for example, the magnetic field bias applied from the fourth magnetic layer 44
to the second magnetic layer 12a is lower than the magnetic field bias applied from the third
magnetic layer 43 to the first magnetic layer 11a. The gauge factor at the second sensing
element 52 is higher than the gauge factor at the first sensing element 51.
[0100]
For example, the first alloy included in the fourth magnetic layer 44 includes (CoxPt100-x) 100yCry. xは、50at. % Or more and 85 at. % Or less. yは、0at. % Or more 40 at. % Or
less.
[0101]
As described below, each of the third magnetic layer 43 and the fourth magnetic layer 44 may
have a laminated film configuration.
04-05-2019
26
[0102]
FIGS. 7A and 7B are schematic perspective views illustrating a portion of another pressure sensor
according to the second embodiment.
The pressure sensor 121 also includes a film unit 70 d, a first sensing element 51, a second
sensing element 52, a third magnetic layer 43, and a fourth magnetic layer 44. FIG. 7A and FIG.
7B illustrate the third magnetic layer 43 and the fourth magnetic layer 44 in the pressure sensor
121.
[0103]
As shown in FIG. 7A, the third magnetic layer 43 includes a first film 43p and a second film 43q.
As shown in FIG. 7B, the fourth magnetic layer 44 includes a third film 44p and a fourth film
44q. The other configuration of the pressure sensor 121 is similar to that of the pressure sensor
120 or the pressure sensor 110, and thus the description thereof is omitted. Hereinafter, these
films will be described.
[0104]
In the third magnetic layer 43, the first film 43p contains at least one of Fe, Co, and Ni. The
second film 43 q is made of Ir-Mn, Pt-Mn, Pd-Pt-Mn, Ru-Mn, Rh-Mn, Ru-Rh-Mn, Fe-Mn, Ni-Mn, CrMn-Pt, and It contains at least one selected from the group consisting of Ni-O.
[0105]
In the fourth magnetic layer 44, the third film 44p contains at least one of Fe, Co, and Ni. The
fourth film 44 q may be Ir-Mn, Pt-Mn, Pd-Pt-Mn, Ru-Mn, Rh-Mn, Ru-Rh-Mn, Fe-Mn, Ni-Mn, CrMn-Pt, and It contains at least one selected from the group consisting of Ni-O.
04-05-2019
27
[0106]
For example, the second film 43 q overlaps the first film 43 p in the first direction (Z-axis
direction). The fourth film 44 q overlaps the third film 44 p in the first direction.
[0107]
The third magnetic layer 43 having such a configuration can, for example, apply a magnetic field
bias to the first magnetic layer 11a. The fourth magnetic layer 44 can, for example, apply a
magnetic field bias to the second magnetic layer 12a.
[0108]
Then, different configurations are applied to the third magnetic layer 43 and the fourth magnetic
layer 44. For example, the fourth magnetic layer 44 has a fourth length L4 along a first direction
different from the first length L1 of the third magnetic layer 43, and a second length L2 different
from the second length L2 of the third magnetic layer 43. A fifth length L5 along the direction, a
sixth length L6 along the third direction different from the third length L3 of the third magnetic
layer 43, and a second magnetism different from the first distance d1 of the third magnetic layer
43 The second distance d2 between the layer 12a and the fourth magnetic layer 44, the second
composition different from the first composition of the third magnetic layer 43, and the fourth
composition different from the third magnetization direction of the third magnetic layer 43 It has
at least one of the magnetization directions. Also in this case, the first distance d1 is shorter than
the distance d3 between the first magnetic layer 11a and the fourth magnetic layer 44. The
second distance d2 is shorter than the distance d4 between the second magnetic layer 12a and
the third magnetic layer 43.
[0109]
By using the third magnetic layer 43 and the fourth magnetic layer 44 having such a
configuration, the characteristics (for example, gauge factor) of the second sensing element 52
can be described as the characteristics (for example, gauge factor) of the first sensing element 51
, Different. According to the embodiment, a pressure sensor capable of expanding the dynamic
range can be provided.
04-05-2019
28
[0110]
At least one of the first film 43p and the third film 44p may include an alloy including at least
one material selected from the group consisting of Co, Fe, and Ni. For example, at least one of the
first film 43p and the third film 44p is a Co x Fe 100-x alloy (x is 0 at. % To 100 at. % Or less), Ni
x Fe 100-x alloy (x is 0 at. % To 100 at. % Or less) or a material obtained by adding a
nonmagnetic element thereto. At least one of the first film 43p and the third film 44p is made of
(CoxFe100-x) 100-yBy alloy (x is 0 at. % To 100 at. % Or less, y is 0 at. % To 30 at. %) May be
included. The characteristics between the strain sensing elements even when the size of the
sensing element is small because at least one of the first film 43p and the third film 44p contains
an amorphous alloy of (CoxFe100-x) 100-yBy. Can be suppressed.
[0111]
The second film 43 q gives uni-directional anisotropy (unidirectional anisotropy), for example, to
the first film 43 p. The second film 43 q fixes, for example, the magnetization of the first film 43
p. The fourth film 44 q imparts, for example, unidirectional anisotropy to the third film 44 p. The
fourth film 44 q fixes, for example, the magnetization of the third film 44 p. At least one of the
first film 43p and the third film 44p includes, for example, an antiferromagnetic layer.
[0112]
The pressure sensor 121 can also provide a pressure sensor capable of expanding the dynamic
range.
[0113]
Generally, in a spin strain sensor, the strain range in which a high gauge factor can be obtained is
limited.
For example, if the gauge factor is high, the operating distortion range (detectable distortion
range) is narrowed. For example, when a pressure sensor is applied to a microphone, if it is
designed to obtain a high gauge factor and a high NS ratio at a normal sound volume, the sound
04-05-2019
29
volume deviates from the operating distortion range of the sensor. For this reason, the signal
corresponding to the detected sound is distorted.
[0114]
On the other hand, in the pressure sensors according to the first and second embodiments
described above, for example, a plurality of sensing elements having different strain sensitivities
(gauge factors) are provided. High sensitivity and wide dynamic range are provided. For example,
spin strain sensors with different strain sensitivities are disposed on the diaphragm. In the case
of normal volume, detection is performed by a high gauge factor detection element, and in the
case of high volume, detection is performed by a low gauge factor detection element. This
provides high sensitivity and wide dynamic range.
[0115]
Hereinafter, examples of sensing elements used in the first and second embodiments will be
described. In the following description, the description of material A / material B indicates a
state in which the layer of material B is provided on the layer of material A.
[0116]
FIG. 8 is a schematic perspective view illustrating a part of the pressure sensor according to the
embodiment. As shown in FIG. 8, in the sensing element 50A, the lower electrode 204, the
underlayer 205, the pinning layer 206, the second magnetization fixed layer 207, the magnetic
coupling layer 208, the first magnetization fixed layer 209, and the middle The layer 203, the
magnetization free layer 210, the cap layer 211, and the upper electrode 212 are arranged in
this order. The first magnetization fixed layer 209 corresponds to, for example, one of the first
opposing magnetic layer 11 b and the second opposing magnetic layer 12 b. The magnetization
free layer 210 corresponds to, for example, one of the first magnetic layer 11a and the second
magnetic layer 12a. The intermediate layer 203 corresponds to one of the first intermediate
layer 11c and the second intermediate layer 12c. The lower electrode 204 corresponds to, for
example, the second electrode 58 b. The upper electrode 212 corresponds to, for example, the
first electrode 58a. The sensing element 50A is, for example, a bottom spin valve type.
04-05-2019
30
[0117]
For the base layer 205, for example, a laminated film (Ta / Ru) of tantalum and ruthenium is
used. The thickness (length in the Z-axis direction) of this Ta layer is, for example, 3 nanometers
(nm). The thickness of this Ru layer is, for example, 2 nm. For the pinning layer 206, for example,
an IrMn layer with a thickness of 7 nm is used. For the second magnetization fixed layer 207, for
example, a Co 75 Fe 25 layer with a thickness of 2.5 nm is used. For the magnetic coupling layer
208, for example, a Ru layer with a thickness of 0.9 nm is used. For the first magnetization fixed
layer 209, for example, a Co 40 Fe 40 B 20 layer with a thickness of 3 nm is used. For the
intermediate layer 203, for example, an MgO layer having a thickness of 1.6 nm is used. For the
magnetization free layer 210, for example, 4 nm thick Co 40 Fe 40 B 20 is used. For the cap
layer 211, for example, Ta / Ru is used. The thickness of this Ta layer is, for example, 1 nm. The
thickness of this Ru layer is, for example, 5 nm.
[0118]
For the lower electrode 204 and the upper electrode 212, for example, at least one of aluminum
(Al), aluminum-copper alloy (Al-Cu), copper (Cu), silver (Ag), and gold (Au) is used. By using such
a material having a relatively small electric resistance as the lower electrode 204 and the upper
electrode 212, current can be efficiently supplied to the sensing element 50A. Nonmagnetic
materials are used for the lower electrode 204 and the upper electrode 212.
[0119]
The lower electrode 204 and the upper electrode 212 are, for example, an underlayer (not
shown) for the lower electrode 204 and the upper electrode 212, a cap layer (not shown) for the
lower electrode 204 and the upper electrode 212, and the like And at least one of Al, Al-Cu, Cu,
Ag, and Au. For example, tantalum (Ta) / copper (Cu) / tantalum (Ta) or the like is used for the
lower electrode 204 and the upper electrode 212. By using Ta as the base layer of the lower
electrode 204 and the upper electrode 212, for example, the adhesion between the substrate (for
example, the film portion 70d) and the lower electrode 204 and the upper electrode 212 is
improved. As a base layer for the lower electrode 204 and the upper electrode 212, titanium (Ti),
titanium nitride (TiN), or the like may be used.
[0120]
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31
By using Ta as a cap layer of the lower electrode 204 and the upper electrode 212, oxidation of
copper (Cu) or the like under the cap layer is suppressed. As a cap layer for the lower electrode
204 and the upper electrode 212, titanium (Ti), titanium nitride (TiN), or the like may be used.
[0121]
For the base layer 205, for example, a laminated structure including a buffer layer (not shown)
and a seed layer (not shown) is used. The buffer layer relieves, for example, surface roughness of
the lower electrode 204, the film portion 70d, and the like, and improves the crystallinity of a
layer stacked on the buffer layer. The buffer layer is, for example, at least one selected from the
group consisting of tantalum (Ta), titanium (Ti), vanadium (V), tungsten (W), zirconium (Zr),
hafnium (Hf) and chromium (Cr). Is used. As the buffer layer, an alloy containing at least one
material selected from these materials may be used.
[0122]
The thickness of the buffer layer in the base layer 205 is preferably 1 nm or more and 10 nm or
less. The thickness of the buffer layer is more preferably 1 nm or more and 5 nm or less. If the
thickness of the buffer layer is too thin, the buffer effect is lost. When the thickness of the buffer
layer is too thick, the thickness of the sensing element 50A becomes excessively thick. A seed
layer is formed on the buffer layer, for example, the seed layer has a buffer effect. In this case,
the buffer layer may be omitted. For the buffer layer, for example, a Ta layer having a thickness
of 3 nm is used.
[0123]
The seed layer in the base layer 205 controls the crystal orientation of the layer stacked on the
seed layer. The seed layer controls the grain size of the layer laminated on the seed layer. As this
seed layer, fcc structure (face-centered cubic structure: face-centered cubic lattice structure), hcp
structure (hexagonal close-packed structure: hexagonal close-packed lattice structure) or bcc
structure (body-centered cubic structure: body-centered cubic lattice) Metal of the structure) is
used.
04-05-2019
32
[0124]
By using ruthenium (Ru) of hcp structure, NiFe of fcc structure, or Cu of fcc structure as the seed
layer of the underlayer 205, for example, the crystal orientation of the spin valve film on the seed
layer is determined. It can be fcc (111) oriented. For the seed layer, for example, a Cu layer with a
thickness of 2 nm or a Ru layer with a thickness of 2 nm is used. When the crystal orientation of
the layer formed on the seed layer is to be enhanced, the thickness of the seed layer is preferably
1 nm or more and 5 nm or less. The thickness of the seed layer is more preferably 1 nm or more
and 3 nm or less. Thereby, the function as a seed layer which improves crystal orientation is fully
exhibited.
[0125]
On the other hand, for example, when it is not necessary to crystallize the layer formed on the
seed layer (for example, when forming an amorphous magnetization free layer), the seed layer
may be omitted. As a seed layer, for example, a Ru layer with a thickness of 2 nm is used.
[0126]
The pinning layer 206 applies unidirectional anisotropy (unidirectional anisotropy) to the second
magnetization fixed layer 207 (ferromagnetic layer) formed on the pinning layer 206, for
example. Fix the magnetization. For the pinning layer 206, for example, an antiferromagnetic
layer is used. For the pinning layer 206, for example, Ir-Mn, Pt-Mn, Pd-Pt-Mn, Ru-Mn, Rh-Mn, RuRh-Mn, Fe-Mn, Ni-Mn, Cr-Mn-Pt and At least one selected from the group consisting of Ni-O is
used. Selected from the group consisting of Ir-Mn, Pt-Mn, Pd-Pt-Mn, Ru-Mn, Rh-Mn, Ru-Rh-Mn,
Fe-Mn, Ni-Mn, Cr-Mn-Pt and Ni-O An alloy in which an additional element is further added to at
least one of the above may be used. The thickness of the pinning layer 206 is appropriately set.
This provides, for example, a sufficiently strong unidirectional anisotropy.
[0127]
For example, heat treatment is performed while applying a magnetic field. Thereby, for example,
the magnetization of the ferromagnetic layer in contact with the pinning layer 206 is fixed. The
04-05-2019
33
magnetization of the ferromagnetic layer in contact with the pinning layer 206 is fixed in the
direction of the magnetic field applied during the heat treatment. The heat treatment
temperature (annealing temperature) is, for example, equal to or higher than the magnetization
fixation temperature of the antiferromagnetic material used for the pinning layer 206. When an
antiferromagnetic layer containing Mn is used, Mn may diffuse into a layer other than the
pinning layer 206 to reduce the MR ratio. The heat treatment temperature is preferably set to a
temperature at which the diffusion of Mn occurs. The heat treatment temperature is, for example,
200 ° C. or more and 500 ° C. or less. The heat treatment temperature is, for example,
preferably 250 ° C. or more and 400 ° C. or less.
[0128]
When PtMn or PdPtMn is used as the pinning layer 206, the thickness of the pinning layer 206
is preferably 8 nm or more and 20 nm or less. The thickness of the pinning layer 206 is more
preferably 10 nm or more and 15 nm or less. When IrMn is used as the pinning layer 206,
unidirectional anisotropy can be imparted with a thinner thickness than when PtMn is used as
the pinning layer 206. In this case, the thickness of the pinning layer 206 is preferably 4 nm or
more and 18 nm or less. The thickness of the pinning layer 206 is more preferably 5 nm or more
and 15 nm or less. For the pinning layer 206, for example, an Ir 22 Mn 78 layer with a thickness
of 7 nm is used.
[0129]
A hard magnetic layer may be used as the pinning layer 206. As the hard magnetic layer, for
example, Co-Pt, Fe-Pt, Co-Pd, or Fe-Pd may be used. In these materials, for example, magnetic
anisotropy and coercivity are relatively high. These materials are hard magnetic materials. As the
pinning layer 206, Co-Pt, Fe-Pt, Co-Pd, or an alloy obtained by adding an additional element to
Fe-Pd may be used. For example, CoPt (Co ratio is 50 at. % Or more and 85 at. % Or less),
(CoxPt100-x) 100-yCry (x is 50 at. % Or more and 85 at. % Or less, y is 0 at. % Or more 40 at. %
Or less) or FePt (the ratio of Pt is 40 at. % Or more 60 at. %) Or the like may be used.
[0130]
In the second magnetization fixed layer 207, for example, a Co x Fe 100-x alloy (x is 0 at. % To
100 at. % Or less) or a Ni x Fe 100-x alloy (x is 0 at.%). % To 100 at. %) Is used. Materials
04-05-2019
34
obtained by adding nonmagnetic elements to these materials may be used. As the second
magnetization fixed layer 207, for example, at least one selected from the group consisting of Co,
Fe, and Ni is used. As the second magnetization fixed layer 207, an alloy containing at least one
material selected from these materials may be used. As the second magnetization fixed layer 207,
a (CoxFe100-x) 100-yBy alloy (x is 0 at. % To 100 at. % Or less, y is 0 at. % To 30 at. % Or less)
can also be used. By using an amorphous alloy of (Co x Fe 100 -x) 100 -y B y as the second
magnetization fixed layer 207, it is possible to suppress the variation in the characteristics of the
sensing element 50A even when the size of the sensing element is small. Can.
[0131]
The thickness of the second magnetization fixed layer 207 is preferably, for example, 1.5 nm or
more and 5 nm or less. Thereby, for example, the strength of the unidirectional anisotropic
magnetic field by the pinning layer 206 can be made stronger. For example, increasing the
strength of the antiferromagnetic coupling magnetic field between the second magnetization
fixed layer 207 and the first magnetization fixed layer 209 via the magnetic coupling layer
formed on the second magnetization fixed layer 207. Can. For example, it is preferable that the
magnetic film thickness of the second magnetization fixed layer 207 (product of saturated
magnetization Bs and thickness t (Bs · t)) be substantially equal to the magnetic film thickness of
the first magnetization fixed layer 209 .
[0132]
The saturation magnetization of Co 40 Fe 40 B 20 in a thin film is about 1.9 T (Tesla). For
example, when a 3 nm thick Co 40 Fe 40 B 20 layer is used as the first magnetization fixed layer
209, the magnetic thickness of the first magnetization fixed layer 209 is 1.9 T × 3 nm, 5.7 T nm,
Become. On the other hand, the saturation magnetization of Co 75 Fe 25 is about 2.1 T. The
thickness of the second magnetization fixed layer 207 at which the magnetic film thickness equal
to the above is obtained is 5.7 Tnm / 2.1T, which is 2.7 nm. In this case, as the second
magnetization fixed layer 207, it is preferable to use a Co 75 Fe 25 layer having a thickness of
about 2.7 nm. As the second magnetization fixed layer 207, for example, a Co 75 Fe 25 layer
with a thickness of 2.5 nm is used.
[0133]
04-05-2019
35
In the sensing element 50A, a synthetic pin structure is used by the second magnetization fixed
layer 207, the magnetic coupling layer 208, and the first magnetization fixed layer 209. Instead,
a single pin structure of one magnetization fixed layer may be used. When a single pin structure
is used, for example, a Co 40 Fe 40 B 20 layer with a thickness of 3 nm is used as the
magnetization fixed layer. The same material as the material of the second magnetization fixed
layer 207 described above may be used as the ferromagnetic layer used for the magnetization
fixed layer of the single pin structure.
[0134]
The magnetic coupling layer 208 causes antiferromagnetic coupling between the second
magnetization fixed layer 207 and the first magnetization fixed layer 209. The magnetic coupling
layer 208 forms a synthetic pin structure. As a material of the magnetic coupling layer 208, for
example, Ru is used. The thickness of the magnetic coupling layer 208 is preferably, for example,
0.8 nm or more and 1 nm or less. A material other than Ru may be used as the magnetic coupling
layer 208 as long as it is a material that causes sufficient antiferromagnetic coupling between the
second magnetization fixed layer 207 and the first magnetization fixed layer 209. The thickness
of the magnetic coupling layer 208 is set to, for example, a thickness of 0.8 nm or more and 1
nm or less corresponding to a second peak (2nd peak) of RKKY (Ruderman-Kittel-Kasuya-Yosida)
bonding. Furthermore, the thickness of the magnetic coupling layer 208 may be set to a
thickness of 0.3 nm or more and 0.6 nm or less corresponding to the first peak (1st peak) of the
RKKY bond. As a material of the magnetic coupling layer 208, for example, Ru having a thickness
of 0.9 nm is used. Thereby, a reliable connection can be obtained more stably.
[0135]
The magnetic layer used for the first magnetization fixed layer 209 directly contributes to the
MR effect. As the first magnetization fixed layer 209, for example, a Co-Fe-B alloy is used.
Specifically, as the first magnetization fixed layer 209, a (CoxFe100-x) 100-yBy alloy (x is 0 at. %
To 100 at. % Or less, y is 0 at. % To 30 at. % Or less) can also be used. In the case where an
amorphous alloy of (Co x Fe 100 -x) 100 -y B y is used as the first magnetization fixed layer 209,
for example, even when the size of the sensing element 50A is small, an element caused by
crystal grains It is possible to suppress the variation between them.
[0136]
04-05-2019
36
A layer (for example, a tunnel insulating layer (not shown)) formed on the first magnetization
fixed layer 209 can be planarized. Planarization of the tunnel insulating layer can reduce the
defect density of the tunnel insulating layer. This results in a higher MR ratio with lower areal
resistance. For example, in the case of using MgO as the material of the tunnel insulating layer, it
is possible to use an amorphous alloy of (CoxFe100-x) 100-yBy as the first magnetization fixed
layer 209 on the tunnel insulating layer. The (100) orientation of the MgO layer to be formed can
be intensified. By making the (100) orientation of the MgO layer higher, a larger MR change rate
can be obtained. The (Co x Fe 100 -x) 100 -y B y alloy crystallizes with the (100) plane of the
MgO layer as a template during annealing. Therefore, good crystal matching between MgO and
the (CoxFe100-x) 100-yBy alloy can be obtained. By obtaining a good crystal alignment, a larger
MR ratio can be obtained.
[0137]
As the first magnetization fixed layer 209, for example, an Fe--Co alloy may be used other than
the Co--Fe--B alloy.
[0138]
When the first magnetization fixed layer 209 is thicker, a larger MR ratio is obtained.
If the first magnetization fixed layer 209 is thin, for example, a larger fixed magnetic field can be
obtained. There is a trade-off relationship in the thickness of the first magnetization fixed layer
209 between the MR ratio and the fixed magnetic field. When a Co̶Fe̶B alloy is used as the
first magnetization fixed layer 209, the thickness of the first magnetization fixed layer 209 is
preferably 1.5 nm or more and 5 nm or less. The thickness of the first magnetization fixed layer
209 is more preferably 2.0 nm or more and 4 nm or less.
[0139]
For the first magnetization fixed layer 209, in addition to the above-described materials, a Co 90
Fe 10 alloy of fcc structure, Co of hcp structure, or Co alloy of hcp structure is used. As the first
magnetization fixed layer 209, for example, at least one selected from the group consisting of Co,
Fe, and Ni is used. As the first magnetization fixed layer 209, an alloy containing at least one
material selected from these materials is used. By using, as the first magnetization fixed layer
04-05-2019
37
209, a FeCo alloy material of bcc structure, a Co alloy containing 50% or more of cobalt
composition, or a material of 50% or more of Ni composition (Ni alloy), for example, a larger MR
The rate of change is obtained.
[0140]
As the first magnetization fixed layer 209, for example, Co 2 MnGe, Co 2 FeGe, Co 2 MnSi, Co 2
FeSi, Co 2 MnAl, Co 2 FeAl, Co 2 MnGa 0.5 Ge 0.5, and Co 2 FeGa A Heusler magnetic alloy layer
such as 0.5 Ge 0.5 can also be used. For example, a Co 40 Fe 40 B 20 layer with a thickness of 3
nm is used as the first magnetization fixed layer 209, for example.
[0141]
The intermediate layer 203 breaks the magnetic coupling between the first magnetization fixed
layer 209 and the magnetization free layer 210, for example.
[0142]
As a material of the intermediate layer 203, for example, a metal, an insulator or a semiconductor
is used.
As the metal, for example, Cu, Au or Ag is used. When a metal is used as the intermediate layer
203, the thickness of the intermediate layer is, for example, about 1 nm or more and 7 nm or
less. As this insulator or semiconductor, for example, magnesium oxide (such as MgO), aluminum
oxide (such as Al2O3), titanium oxide (such as TiO), zinc oxide (such as ZnO), or gallium oxide
(such as Ga- O) etc. are used. When an insulator or a semiconductor is used as the intermediate
layer 203, the thickness of the intermediate layer 203 is, for example, about 0.6 nm or more and
2.5 nm or less. As the intermediate layer 203, for example, a CCP (Current-Confined-Path) spacer
layer may be used. When a CCP spacer layer is used as a spacer layer, for example, a structure in
which a copper (Cu) metal path is formed in an insulating layer of aluminum oxide (Al2O3) is
used. For example, a MgO layer with a thickness of 1.6 nm is used as the intermediate layer.
[0143]
04-05-2019
38
A ferromagnetic material is used for the magnetization free layer 210. For the magnetization free
layer 210, for example, a ferromagnetic material containing Fe, Co, Ni is used. As a material of
the magnetization free layer 210, for example, a FeCo alloy, a NiFe alloy or the like is used.
Furthermore, in the magnetization free layer 210, a Co-Fe-B alloy, an Fe-Co-Si-B alloy, an Fe-Ga
alloy having a large λs (magnetostriction constant), an Fe-Co-Ga alloy, a Tb-M-Fe alloy , Tb-M1Fe-M2 alloy, Fe-M3-M4-B alloy, Ni, Fe-Al, or ferrite is used. In these materials, for example, λs
(magnetostriction constant) is large. In the above-mentioned Tb-M-Fe alloy, M is at least one
selected from the group consisting of Sm, Eu, Gd, Dy, Ho and Er. In the above-mentioned Tb-M1Fe-M2 alloy, M1 is at least one selected from the group consisting of Sm, Eu, Gd, Dy, Ho and Er.
M2 is at least one selected from the group consisting of Ti, Cr, Mn, Co, Cu, Nb, Mo, W and Ta. In
the above Fe-M3-M4-B alloy, M3 is at least one selected from the group consisting of Ti, Cr, Mn,
Co, Cu, Nb, Mo, W and Ta. M4 is at least one selected from the group consisting of Ce, Pr, Nd, Sm,
Tb, Dy and Er. As said ferrite, Fe3O4, (FeCo) 3O4 etc. are mentioned. The thickness of the
magnetization free layer 210 is, for example, 2 nm or more.
[0144]
The magnetic free layer 210 may be made of a magnetic material containing boron. For the
magnetization free layer 210, for example, an alloy containing at least one element selected from
the group consisting of Fe, Co and Ni and boron (B) may be used. For the magnetization free
layer 210, for example, a Co-Fe-B alloy or an Fe-B alloy is used. For example, a Co40Fe40B20
alloy is used. When an alloy containing at least one element selected from the group consisting of
Fe, Co and Ni and boron (B) is used for the magnetization free layer 210, Ga, Al, Si, or W is added.
Also good. The addition of these elements promotes, for example, high magnetostriction. As the
magnetization free layer 210, for example, an Fe-Ga-B alloy, a Fe-Co-Ga-B alloy, or an Fe-Co-Si-B
alloy may be used. By using such a boron-containing magnetic material, the coercivity (Hc) of the
magnetization free layer 210 becomes low, and the change of the magnetization direction with
respect to strain becomes easy. This provides high sensitivity.
[0145]
The boron concentration (for example, the composition ratio of boron) in the magnetization free
layer 210 is 5 at. % (Atomic percent) or more is preferable. This makes it easy to obtain an
amorphous structure. The boron concentration in the magnetization free layer is 35 at. % Or less
is preferable. If the boron concentration is too high, for example, the magnetostriction constant
decreases. The boron concentration in the magnetization free layer is, for example, 5 at. % Or
more 35 at. % Or less is preferable, and 10 at. % To 30 at. % Or less is more preferable.
04-05-2019
39
[0146]
In a part of the magnetic layer of the magnetization free layer 210, Fe 1-y B y (0 <y ≦ 0.3), or
(Fez x 1-a) 1-y B y (X is Co or Ni, When 0.8 ≦ z <1, 0 <y ≦ 0.3, it is easy to simultaneously
achieve a large magnetostriction constant λ and a low coercivity. For this reason, it is
particularly preferable in view of obtaining a high gauge factor. For example, Fe 80 B 20 (4 nm)
is used as the magnetization free layer 210. As the magnetization free layer, Co40Fe40B20 (0.5
nm) / Fe80B20 (4 nm) is used.
[0147]
The magnetization free layer 210 may have a multilayer structure. When a tunnel insulating
layer of MgO is used as the intermediate layer 203, a layer of a Co-Fe-B alloy is preferably
provided in a portion of the magnetization free layer 210 in contact with the intermediate layer
203. Thereby, a high magnetoresistance effect can be obtained. In this case, a layer of a Co-Fe-B
alloy is provided on the intermediate layer 203, and another magnetic material having a large
magnetostriction constant is provided on the layer of the Co-Fe-B alloy. When the magnetization
free layer 210 has a multilayer structure, for example, Co-Fe-B (2 nm) / Fe-Co-Si-B (4 nm) or the
like is used for the magnetization free layer 210.
[0148]
The cap layer 211 protects a layer provided under the cap layer 211. For the cap layer 211, for
example, a plurality of metal layers are used. For the cap layer 211, for example, a two-layer
structure (Ta / Ru) of a Ta layer and a Ru layer is used. The thickness of this Ta layer is, for
example, 1 nm, and the thickness of this Ru layer is, for example, 5 nm. As the cap layer 211,
another metal layer may be provided instead of the Ta layer or the Ru layer. The configuration of
the cap layer 211 is arbitrary. For example, a nonmagnetic material is used as the cap layer 211.
Other materials may be used as the cap layer 211 as long as the layer provided below the cap
layer 211 can be protected.
[0149]
04-05-2019
40
When a magnetic material containing boron is used for the magnetization free layer 210, a
diffusion suppression layer (not shown) of an oxide material or a nitride material may be
provided between the magnetization free layer 210 and the cap layer 211. Thereby, for example,
the diffusion of boron is suppressed. By using a diffusion suppression layer including an oxide
layer or a nitride layer, diffusion of boron contained in the magnetization free layer 210 can be
suppressed, and the amorphous structure of the magnetization free layer 210 can be maintained.
As an oxide material or nitride material used for the diffusion suppression layer, for example, Mg,
Al, Si, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Zr, Nb, Mo, Ru, Rh An oxide material or nitride material
containing an element such as Pd, Ag, Hf, Ta, W, Sn, Cd or Ga is used. The diffusion suppression
layer is a layer that does not contribute to the magnetoresistance effect. The area resistance of
the diffusion suppression layer is preferably low. For example, the area resistance of the diffusion
suppression layer is preferably set lower than the area resistance of the intermediate layer
contributing to the magnetoresistance effect. From the viewpoint of reducing the area resistance
of the diffusion suppression layer, an oxide or a nitride of Mg, Ti, V, Zn, Sn, Cd, or Ga is
preferable for the diffusion suppression layer. The barrier height is low in these materials. As a
function to suppress the diffusion of boron, an oxide having a stronger chemical bond is
preferable. For example, a 1.5 nm MgO layer is used. The oxynitride is contained in either the
oxide or the nitride.
[0150]
When an oxide or a nitride is used for the diffusion suppression layer, the thickness of the
diffusion suppression layer is preferably, for example, 0.5 nm or more. Thus, the diffusion
suppressing function of boron is sufficiently exerted. The thickness of the diffusion suppression
layer is preferably 5 nm or less. Thereby, for example, low area resistance can be obtained. The
thickness of the diffusion suppression layer is preferably 0.5 nm or more and 5 nm or less, and
more preferably 1 nm or more and 3 nm or less.
[0151]
As the diffusion suppression layer, at least one selected from the group consisting of magnesium
(Mg), silicon (Si) and aluminum (Al) may be used. A material containing these light elements is
used as the diffusion suppression layer. These light elements combine with boron to form a
compound. For example, at least one of a Mg-B compound, an Al-B compound, and a Si-B
compound is formed in a portion including the interface between the diffusion suppression layer
and the magnetization free layer 210. These compounds suppress the diffusion of boron.
04-05-2019
41
[0152]
Another metal layer or the like may be inserted between the diffusion suppression layer and the
magnetization free layer 210. If the distance between the diffusion suppression layer and the
magnetization free layer 210 is too large, boron diffuses between them and the boron
concentration in the magnetization free layer 210 decreases. Therefore, the distance between the
diffusion suppression layer and the magnetization free layer 210 is preferably 10 nm or less, and
more preferably 3 nm or less.
[0153]
FIG. 9 is a schematic perspective view illustrating a portion of another pressure sensor according
to the embodiment. As shown in FIG. 9, the sensing element 50AA is the same as the sensing
element 50A except that the insulating layer 213 is provided. The insulating layer 213 is
provided between the lower electrode 204 and the upper electrode 212. The insulating layer 213
is aligned with the magnetization free layer 210 and the first magnetization fixed layer 209 in a
direction intersecting the direction connecting the lower electrode 204 and the upper electrode
212. The portions other than the insulating layer 213 are the same as those of the detection
element 50A, and thus the description thereof is omitted.
[0154]
For the insulating layer 213, for example, aluminum oxide (for example, Al 2 O 3), silicon oxide
(for example, SiO 2), or the like is used. The insulating layer 213 suppresses the leak current of
the sensing element 50AA. The insulating layer 213 may be provided in a detection element
described later.
[0155]
FIG. 10 is a schematic perspective view illustrating a portion of another pressure sensor
according to the embodiment. As shown in FIG. 10, a hard bias layer 214 is further provided in
the sensing element 50AB. Except this, it is the same as that of sensing element 50A. The hard
04-05-2019
42
bias layer 214 is provided between the lower electrode 204 and the upper electrode 212. The
magnetization free layer 210 and the first magnetization fixed layer 209 are disposed between
two portions of the hard bias layer 214 in a direction intersecting the direction connecting the
lower electrode 204 and the upper electrode 212. Except this, it is the same as that of sensing
element 50AA.
[0156]
The hard bias layer 214 sets the magnetization direction of the magnetization free layer 210 by
the magnetization of the hard bias layer 214. With the hard bias layer 214, the magnetization
direction of the magnetization free layer 210 is set to a desired direction in a state where no
external pressure is applied to the film portion 70d.
[0157]
For the hard bias layer 214, for example, Co-Pt, Fe-Pt, Co-Pd, or Fe-Pd is used. In these materials,
for example, magnetic anisotropy and coercivity are relatively high. These materials are, for
example, hard magnetic materials. For the hard bias layer 214, for example, an alloy in which an
additive element is further added to Co-Pt, Fe-Pt, Co-Pd, or Fe-Pd may be used. In the hard bias
layer 214, for example, CoPt (Co ratio is 50 at. % Or more and 85 at. % Or less), (CoxPt100-x)
100-yCry (x is 50 at. % Or more and 85 at. % Or less, y is 0 at. % Or more 40 at. % Or less) or
FePt (the ratio of Pt is 40 at. % Or more 60 at. %) Or the like may be used. When such a material
is used, the direction of magnetization of the hard bias layer 214 is set (fixed) in the direction in
which the external magnetic field is applied by applying an external magnetic field larger than
the coercivity of the hard bias layer 214. The thickness (for example, the length along the
direction from the lower electrode 204 toward the upper electrode) of the hard bias layer 214 is,
for example, 5 nm or more and 50 nm or less.
[0158]
When the insulating layer 213 is disposed between the lower electrode 204 and the upper
electrode 212, SiO x or AlO x is used as a material of the insulating layer 213. Further, an
underlayer (not shown) may be provided between the insulating layer 213 and the hard bias
layer 214. When a hard magnetic material such as Co-Pt, Fe-Pt, Co-Pd, or Fe-Pd is used for the
hard bias layer 214, Cr or Fe-Co is used as a material of the underlayer for the hard bias layer
04-05-2019
43
214. Etc. are used.
[0159]
The hard bias layer 214 may have a structure stacked on a hard bias layer pinning layer (not
shown). In this case, the magnetization direction of the hard bias layer 214 can be set (fixed) by
exchange coupling between the hard bias layer 214 and the pinning layer for hard bias layer. In
this case, the hard bias layer 214 is made of a ferromagnetic material of an alloy containing at
least one of Fe, Co and Ni, or at least one of them. In this case, for the hard bias layer 214, for
example, a Co x Fe 100-x alloy (x is 0 at. % To 100 at. % Or less), Ni x Fe 100-x alloy (x is 0 at. %
To 100 at. Or less, or materials obtained by adding a nonmagnetic element thereto. As the hard
bias layer 214, the same material as that of the first magnetization fixed layer 209 described
above is used. For the hard bias layer pinning layer, the same material as the pinning layer 206
in the above-mentioned sensing element 50A is used. In the case of providing a hard bias layer
pinning layer, an underlayer similar to the material used for the underlayer 205 may be provided
below the hard bias layer pinning layer. The hard bias layer pinning layer may be provided below
or above the hard bias layer. The magnetization direction of the hard bias layer 214 in this case,
like the pinning layer 206, is determined by heat treatment in a magnetic field.
[0160]
The hard bias layer 214 and the insulating layer 213 described above can be applied to any of
the sensing elements according to the embodiment. When the stacked structure of the hard bias
layer 214 and the hard bias layer pinning layer is used, the magnetization direction of the hard
bias layer 214 is easily maintained even when a large external magnetic field is applied to the
hard bias layer 214 in a short time. be able to.
[0161]
FIG. 11 is a schematic perspective view illustrating a portion of another pressure sensor
according to the embodiment. As shown in FIG. 11, in the sensing element 50B, the lower
electrode 204, the underlayer 205, the magnetization free layer 210, the intermediate layer 203,
the first magnetization fixed layer 209, the magnetic coupling layer 208, and the second
magnetization. The fixed layer 207, the pinning layer 206, the cap layer 211, and the upper
electrode 212 are sequentially stacked. The first magnetization fixed layer 209 corresponds to,
04-05-2019
44
for example, one of the first opposing magnetic layer 11 b and the second opposing magnetic
layer 12 b. The magnetization free layer 210 corresponds to, for example, one of the first
magnetic layer 11a and the second magnetic layer 12a. The intermediate layer 203 corresponds
to one of the first intermediate layer 11c and the second intermediate layer 12c. The sensing
element 50B is, for example, a top spin valve type.
[0162]
As the base layer 205, for example, a laminated film (Ta / Cu) of tantalum and copper is used.
The thickness (length in the Z-axis direction) of this Ta layer is, for example, 3 nm. The thickness
of this Cu layer is, for example, 5 nm. For the magnetization free layer 210, for example, 4 nm
thick Co 40 Fe 40 B 20 is used. For the intermediate layer 203, for example, an MgO layer
having a thickness of 1.6 nm is used. For the first magnetization fixed layer 209, for example,
Co40Fe40B20 / Fe50Co50 is used. The thickness of this Co 40 Fe 40 B 20 layer is, for example,
2 nm. The thickness of this Fe 50 Co 50 layer is, for example, 1 nm. For the magnetic coupling
layer 208, for example, a Ru layer with a thickness of 0.9 nm is used. For the second
magnetization fixed layer 207, for example, a Co 75 Fe 25 layer with a thickness of 2.5 nm is
used. For the pinning layer 206, for example, an IrMn layer with a thickness of 7 nm is used. For
the cap layer 211, for example, Ta / Ru is used. The thickness of this Ta layer is, for example, 1
nm. The thickness of this Ru layer is, for example, 5 nm.
[0163]
The material of each layer included in the sensing element 50B can be used by inverting the
material of each layer included in the sensing element 50A up and down. The above-described
diffusion suppression layer may be provided between the underlayer 205 of the sensing element
50B and the magnetization free layer 210.
[0164]
FIG. 12 is a schematic perspective view illustrating a part of another pressure sensor according
to the embodiment. As shown in FIG. 12, in the sensing element 50C, the lower electrode 204,
the base layer 205, the pinning layer 206, the first magnetization fixed layer 209, the
intermediate layer 203, the magnetization free layer 210, and the cap layer 211. , Are stacked in
this order. The first magnetization fixed layer 209 corresponds to, for example, one of the first
04-05-2019
45
opposing magnetic layer 11 b and the second opposing magnetic layer 12 b. The magnetization
free layer 210 corresponds to, for example, one of the first magnetic layer 11a and the second
magnetic layer 12a. The intermediate layer 203 corresponds to one of the first intermediate
layer 11c and the second intermediate layer 12c. The sensing element 50C has, for example, a
single pin structure using a single magnetization fixed layer.
[0165]
For the base layer 205, for example, Ta / Ru is used. The thickness (length in the Z-axis direction)
of this Ta layer is, for example, 3 nm. The thickness of this Ru layer is, for example, 2 nm. For the
pinning layer 206, for example, an IrMn layer with a thickness of 7 nm is used. For the first
magnetization fixed layer 209, for example, a Co 40 Fe 40 B 20 layer with a thickness of 3 nm is
used. For the intermediate layer 203, for example, an MgO layer having a thickness of 1.6 nm is
used. For the magnetization free layer 210, for example, 4 nm thick Co 40 Fe 40 B 20 is used.
For the cap layer 211, for example, Ta / Ru is used. The thickness of this Ta layer is, for example,
1 nm. The thickness of this Ru layer is, for example, 5 nm.
[0166]
As the material of each layer of the sensing element 50C, for example, the same material as the
material of each layer of the sensing element 50A is used.
[0167]
FIG. 13 is a schematic perspective view illustrating a part of another pressure sensor according
to the embodiment.
As shown in FIG. 13, in the sensing element 50D, the lower electrode 204, the underlayer 205,
the lower pinning layer 221, the lower second magnetization fixed layer 222, the lower magnetic
coupling layer 223, and the lower first magnetization fixed layer 224, lower intermediate layer
225, magnetization free layer 226, upper intermediate layer 227, upper first magnetization fixed
layer 228, upper magnetic coupling layer 229, upper second magnetization fixed layer 230,
upper pinning layer 231 And the cap layer 211 are sequentially stacked. The lower first
magnetization fixed layer 224 and the upper first magnetization fixed layer 228 correspond to,
for example, one of the first opposing magnetic layer 11 b and the second opposing magnetic
layer 12 b. The magnetization free layer 226 corresponds to, for example, one of the first
04-05-2019
46
magnetic layer 11 a and the second magnetic layer 12 a.
[0168]
For the base layer 205, for example, Ta / Ru is used. The thickness (length in the Z-axis direction)
of this Ta layer is, for example, 3 nanometers (nm). The thickness of this Ru layer is, for example,
2 nm. For the lower pinning layer 221, for example, an IrMn layer with a thickness of 7 nm is
used. For the lower second magnetization fixed layer 222, for example, a Co 75 Fe 25 layer with
a thickness of 2.5 nm is used. For the lower magnetic coupling layer 223, for example, a Ru layer
with a thickness of 0.9 nm is used. For the lower first magnetization fixed layer 224, for example,
a Co 40 Fe 40 B 20 layer with a thickness of 3 nm is used. For the lower intermediate layer 225,
for example, an MgO layer having a thickness of 1.6 nm is used. For the magnetization free layer
226, for example, 4 nm thick Co 40 Fe 40 B 20 is used. For the upper intermediate layer 227, for
example, an MgO layer having a thickness of 1.6 nm is used. For the upper first magnetization
fixed layer 228, for example, Co40Fe40B20 / Fe50Co50 is used. The thickness of this Co 40 Fe
40 B 20 layer is, for example, 2 nm. The thickness of this Fe 50 Co 50 layer is, for example, 1 nm.
For the upper magnetic coupling layer 229, for example, a Ru layer with a thickness of 0.9 nm is
used. For the upper second magnetization fixed layer 230, for example, a Co 75 Fe 25 layer with
a thickness of 2.5 nm is used. For the upper pinning layer 231, for example, an IrMn layer with a
thickness of 7 nm is used. For the cap layer 211, for example, Ta / Ru is used. The thickness of
this Ta layer is, for example, 1 nm. The thickness of this Ru layer is, for example, 5 nm.
[0169]
As a material of each layer of sensing element 50D, the thing similar to the material of each layer
of sensing element 50A is used, for example.
[0170]
FIG. 14 is a schematic perspective view illustrating a portion of another pressure sensor
according to the embodiment.
As shown in FIG. 14, in the sensing element 50E, the lower electrode 204, the underlayer 205,
the first magnetization free layer 241, the intermediate layer 203, the second magnetization free
layer 242, the cap layer 211, and the upper electrode And 212 are stacked in this order. The first
magnetization free layer 241 corresponds to one of the first magnetic layer 11 a and the second
04-05-2019
47
magnetic layer 12 a. The second magnetization free layer 242 corresponds to one of the first
opposing magnetic layer 11 b and the second opposing magnetic layer 12 b. In this example, the
magnetizations of the first opposing magnetic layer 11 b and the second opposing magnetic
layer 12 b can be changed.
[0171]
For the base layer 205, for example, Ta / Cu is used. The thickness (length in the Z-axis direction)
of this Ta layer is, for example, 3 nm. The thickness of this Cu layer is, for example, 5 nm. For the
first magnetization free layer 241, for example, Co40Fe40B20 having a thickness of 4 nm is
used. For the intermediate layer 203, for example, Co40Fe40B20 with a thickness of 4 nm is
used in the second example. For example, Cu / Ta / Ru is used for the cap layer 211. The
thickness of this Cu layer is, for example, 5 nm. The thickness of this Ta layer is, for example, 1
nm. The thickness of this Ru layer is, for example, 5 nm.
[0172]
The material of each layer of the sensing element 50E is the same as the material of each layer of
the sensing element 50A. As a material of the first magnetization free layer 241 and the second
magnetization free layer 242, for example, the same material as the magnetization free layer 210
of the sensing element 50A may be used.
[0173]
Third Embodiment FIG. 15 is a schematic view illustrating a microphone according to a third
embodiment. As shown in FIG. 15, the microphone 610 according to the present embodiment
includes any pressure sensor according to the above-described embodiment, or a pressure sensor
according to a modification thereof. In this example, a pressure sensor 110 is used as a pressure
sensor.
[0174]
The microphone 610 is provided, for example, in the portable information terminal 710. The film
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unit 70 d of the pressure sensor 110 is, for example, substantially parallel to the surface of the
portable information terminal 710 on which the display unit 620 is provided. The arrangement
of the film unit 70d is arbitrary. According to the embodiment, it is possible to provide a
microphone whose dynamic range can be expanded. The microphone 610 according to the
embodiment may be provided, for example, in an IC recorder or a pin microphone.
[0175]
FIG. 16 is a schematic cross-sectional view illustrating another microphone according to the third
embodiment. A microphone 320 (acoustic microphone) according to the present embodiment
includes a printed circuit board 321, a cover 323, and a pressure sensor. As a pressure sensor,
any of the pressure sensors according to the embodiments or their variants are used. In this
example, a pressure sensor 110 is used as a pressure sensor. The printed board 321 includes, for
example, a circuit such as an amplifier. The cover 323 is provided with an acoustic hole 325. The
sound 329 enters the inside of the cover 323 through the acoustic hole 325. The microphone
320 is sensitive to sound pressure. By using the highly sensitive pressure sensor 110, a highly
sensitive microphone 320 can be obtained. For example, the pressure sensor 110 is mounted on
the printed circuit board 321, and an electrical signal line is provided. A cover 323 is provided
on the printed circuit board 321 so as to cover the pressure sensor 110. It is possible to provide
a microphone whose dynamic range can be expanded.
[0176]
Fourth Embodiment FIGS. 17A and 17B are schematic views illustrating a blood pressure sensor
according to a fourth embodiment. FIG. 17 (a) is a schematic plan view illustrating the skin on
human arterial blood vessels. FIG.17 (b) is H1-H2 sectional view taken on the line of FIG. 17 (a).
[0177]
The blood pressure sensor 330 according to this embodiment includes any pressure sensor
according to the embodiment or a variation thereof. In this example, a pressure sensor 110 is
used as a pressure sensor. Pressure sensor 110 is pressed against skin 333 above arterial blood
vessel 331. Thereby, the blood pressure sensor 330 can perform blood pressure measurement
continuously. According to the present embodiment, it is possible to provide a blood pressure
sensor capable of expanding the dynamic range. Blood pressure can be measured with high
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sensitivity.
[0178]
Fifth Embodiment FIG. 18 is a schematic view illustrating a touch panel according to a fifth
embodiment. As the touch panel 340 according to the present embodiment, any pressure sensor
according to the embodiment or a modification thereof is used. In this example, a pressure sensor
110 is used as a pressure sensor. In the touch panel 340, the pressure sensor 110 is mounted on
at least one of the inside of the display and the outside of the display.
[0179]
For example, the touch panel 340 includes a plurality of first wires 346, a plurality of second
wires 347, a plurality of pressure sensors 110, and a control unit 341.
[0180]
In this example, the plurality of first wires 346 are arranged along the Y-axis direction.
Each of the plurality of first wires 346 extends along the X-axis direction. The plurality of second
wires 347 are arranged along the X-axis direction. Each of the plurality of second wires 347
extends along the Y-axis direction.
[0181]
Each of the plurality of pressure sensors 110 is provided at each intersection of the plurality of
first wires 346 and the plurality of second wires 347. One of the pressure sensors 110 is one of
the sensing elements 310 e for sensing. Here, the intersection includes a position where the first
wire 346 and the second wire 347 intersect and a region around the position.
[0182]
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One end 310 a of each of the plurality of pressure sensors 110 is connected to each of the
plurality of first wires 346. The other end 310 b of each of the plurality of pressure sensors 110
is connected to each of the plurality of second wires 347.
[0183]
The control unit 341 is connected to the plurality of first wires 346 and the plurality of second
wires 347. For example, the control unit 341 includes a first wiring circuit 346d connected to the
plurality of first wirings 346, a second wiring circuit 347d connected to the plurality of second
wirings 347, and a first wiring circuit 346d. And a control circuit 345 connected to the second
wiring circuit 347d. The pressure sensor 110 is capable of compact and highly sensitive pressure
sensing. Therefore, it is possible to realize a high definition touch panel.
[0184]
According to the embodiment, it is possible to provide a touch panel whose dynamic range can
be expanded. Enables highly sensitive touch input.
[0185]
The pressure sensor according to the embodiment may be applied to an air pressure sensor, a
tire air pressure sensor, or the like in addition to the application described above. The pressure
sensor according to the embodiment can be applied to various pressure detections.
[0186]
According to the embodiment, it is possible to provide a pressure sensor, a microphone, a blood
pressure sensor, and a touch panel whose dynamic range can be expanded.
[0187]
FIG. 19 is a schematic plan view illustrating a pressure sensor.
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51
As shown in FIG. 19, the pressure sensor 130 includes a deformable first film portion 70 da, a
first detection element 51 fixed to the first film portion 70 da, a deformable second film portion
70 db, and a second detection portion 51. And a second detection element 52 fixed to the film
unit 70db. For example, the second material of the second sensing element 52 is different from
the first material of the first sensing element 51. For example, the third magnetic layer 43 and
the fourth magnetic layer 44 may be provided. In this case, the configurations described in
regard to FIG. 6A to FIG. 6D or FIG. 7A and FIG. 7B are applied to the third magnetic layer 43 and
the fourth magnetic layer 44. .
[0188]
In the present specification, "vertical" and "parallel" include not only strictly vertical and strictly
parallel but also include, for example, variations in manufacturing processes, etc., and they may
be substantially vertical and substantially parallel. Just do it.
[0189]
The embodiments of the present invention have been described above with reference to specific
examples.
However, the present invention is not limited to these specific examples. For example, the
specific configuration of each element such as a film unit, a sensing element, a magnetic layer, an
intermediate layer, an electrode, and a processing unit included in a pressure sensor may be
appropriately selected by those skilled in the art from known ranges. As long as the same effect
can be obtained, it is included in the scope of the present invention.
[0190]
Moreover, what combined any two or more elements of each specific example in the technically
possible range is also included in the scope of the present invention as long as the gist of the
present invention is included.
[0191]
In addition, all pressure sensors, microphones, blood pressure sensors and touch panels that can
be appropriately designed and implemented based on the pressure sensors, microphones, blood
pressure sensors and touch panels described above as the embodiments of the present invention
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As long as the scope of the invention is included, it belongs to the scope of the present invention.
[0192]
Besides, within the scope of the concept of the present invention, those skilled in the art can
conceive of various changes and modifications, and it is understood that the changes and
modifications are also within the scope of the present invention. .
[0193]
While certain embodiments of the present invention have been described, these embodiments
have been presented by way of example only, and are not intended to limit the scope of the
invention.
These novel embodiments can be implemented in various other forms, and various omissions,
substitutions, and modifications can be made without departing from the scope of the invention.
These embodiments and modifications thereof are included in the scope and the gist of the
invention, and are included in the invention described in the claims and the equivalent scope
thereof.
[0194]
11a: first magnetic layer, 11b: first opposing magnetic layer, 11c: first intermediate layer, 12a:
second magnetic layer, 12b: second opposing magnetic layer, 12c: second intermediate layer, 43:
third magnetic layer 43a 43b Magnetic layer 43p First film 43q Second film 44 Magnetic layer
44a 44b Magnetic layer 44p Third film 44q Fourth film 50 50A 50AA, 50AB, 50AC, 50B, 50C,
50D,... Sensing elements, 51: first sensing elements, 52: second sensing elements, 58a to 58d,
first to fourth electrodes, 58i: insulating film, 68: processing Portion 70d: Film portion 70da:
First film portion 70db: Second film portion 70h: Cavity 70s: Holding portion 70s1 to s4: First to
fourth sides ε: Strain 110, 120, 121 , 130 ... pressure sensor, 203 ... middle layer, 2 4 lower
electrode 205 lower layer 206 pinning layer 207 second magnetization fixed layer 208 magnetic
coupling layer 209 first magnetization fixed layer 210 magnetization free layer 211 cap layer
212 Upper electrode 213 insulating layer 214 hard bias layer 221 lower pinning layer 222
lower second magnetization fixed layer 223 lower magnetic coupling layer 224 lower first
magnetization fixed layer 225 lower intermediate layer , 226: magnetization free layer, 227:
upper intermediate layer, 228: upper first magnetization fixed layer, 229, upper magnetic
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coupling layer, 230, upper second magnetization fixed layer, 231, upper pinning layer, 241: first
magnetization free Layers 242: second magnetization free layer 310a: one end 310b: other end
310e: detection element 320: microphone 321: printed circuit board 323: cover , 325: acoustic
hole, 329: sound, 330: blood pressure sensor, 331: arterial blood vessel, 333: skin, 340: touch
panel, 341: control unit, 345: control circuit, 346: first wiring, 346 d: for first wiring Circuit 347:
second wiring 347 d: second wiring circuit 610: microphone 620: display unit 710: portable
information terminal AR: arrow Dp: depth GF: gauge factor: Int: strength L1 ˜ L6 ... 1st to 6th
length, Ps ... pressure, R ... electrical resistance, S01, S02 ... 1st and 2nd configuration, d1, d2 ...
1st and 2nd distance, d3, d4 ... distance
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