Microphone package

According to one embodiment, a microphone package includes: a pressure sensing element including a film and a device; and a cover. The film generates strain in response to pressure. The device includes: a first electrode; a second electrode; and a first magnetic layer. The first magnetic layer is provided between the first electrode and the second electrode and has a first magnetization. The cover includes: an upper portion; and a side portion. The side portion is magnetic and provided depending on the first magnetization and the second magnetization.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is based upon and claims the benefit of priority from Japanese Patent Application No. 2012-254357, filed on Nov. 20, 2012; the entire contents of which are incorporated herein by reference.

FIELD

Embodiments described herein relate generally to a microphone package.

BACKGROUND

A magnetoresistive effect element can be used to configure a pressure sensing element. This makes it possible to sense pressure change based on the change of the angle between the magnetization of the magnetization free layer and the magnetization of the reference layer. In a microphone package including a pressure sensing element based on a magnetoresistive effect element, the external magnetic field due to e.g. geomagnetism may act as external noise on at least one of the magnetization of the magnetization free layer and the magnetization of the reference layer.

DETAILED DESCRIPTION

In general, according to one embodiment, a microphone package includes: a pressure sensing element including a film and a device; and a cover. The film generates strain in response to pressure. The device is provided on the film. The device includes: a first electrode; a second electrode; and a first magnetic layer. The first magnetic layer is provided between the first electrode and the second electrode and has a first magnetization. The cover includes: an upper portion; and a side portion. The upper portion is provided with a hole configured to passing sound. The side portion is magnetic and provided depending on the first magnetization and the second magnetization. The cover houses therein the pressure sensing element.

The drawings are schematic or conceptual. The relationship between the thickness and the width of each portion, and the size ratio between the portions, for instance, are not necessarily identical to those in reality. Furthermore, the same portion may be shown with different dimensions or ratios depending on the figures.

In the present specification and the drawings, components similar to those described previously with reference to earlier figures are labeled with like reference numerals, and the detailed description thereof is omitted appropriately.

FIGS. 1A and 1Bare schematic views illustrating the configuration of a microphone package according to a first embodiment.

FIG. 1Ais a schematic plan view.FIG. 1Bis a sectional view taken along line E1-E2ofFIG. 1A.

FIGS. 2A and 2Bare schematic views illustrating the configuration of a microphone package according to a second embodiment.

FIG. 2Ais a sectional view corresponding to the sectional view taken along line E1-E2ofFIG. 1A.FIG. 2Bis a schematic enlarged view of region W1shown inFIG. 2A.

FIGS. 3A and 3Bare schematic views illustrating the configuration of a microphone package according to a third embodiment.

FIG. 3Ais a schematic plan view.FIG. 3Bis a sectional view taken along line A1-A2ofFIG. 3A.

FIGS. 4A and 4Bare schematic views illustrating the configuration of a microphone package according to a fourth embodiment.

FIG. 4Ais a schematic plan view.FIG. 4Bis a sectional view taken along line G1-G2ofFIG. 4A.

The microphone packages111,112,113according to the embodiments are applicable to e.g. a sound pressure sensor.

The microphone package111shown inFIGS. 1A and 1Bincludes a mounting substrate50, a pressure sensing element40, an application specific integrated circuit (ASIC)60, and a cover70.

The mounting substrate50has a first major surface50sand a second major surface50b.

The direction perpendicular to the first major surface50sis referred to as Z-axis direction. One direction perpendicular to the Z-axis direction is referred to as X-axis direction. The direction perpendicular to the Z-axis direction and the X-axis direction is referred to as Y-axis direction. The second major surface50bis spaced from the first major surface50sin the Z-axis direction.

The pressure sensing element40is provided on the first major surface50s. The pressure sensing element40includes a film30and a device25. The integrated circuit60is provided on the first major surface50s. The cover70is provided on the first major surface50sand houses therein the pressure sensing element40and the integrated circuit60. The mounting substrate50is provided with an electrode pad. The electrode pad will be described later.

In this specification, the state of being “provided on” includes not only the state of being provided in direct contact, but also the state of being provided with another element interposed in between.

The cover70has an upper portion (lid portion)74, a first side portion75, a second side portion76, a third side portion77, and a fourth side portion78. The upper portion74has a surface substantially perpendicular to the Z-axis direction. The first side portion75has a surface non-parallel to the direction perpendicular to the Z-axis direction. In this example, the first side portion75has a surface substantially perpendicular to the direction perpendicular to the Z-axis direction. In other words, the first side portion75has a surface substantially parallel to the Z-axis direction. The second side portion76has a surface non-parallel to the direction perpendicular to the Z-axis direction. In this example, the second side portion76has a surface substantially perpendicular to the direction perpendicular to the Z-axis direction. In other words, the second side portion76has a surface substantially parallel to the Z-axis direction. The third side portion77has a surface non-parallel to the direction perpendicular to the Z-axis direction. In this example, the third side portion77has a surface substantially perpendicular to the direction perpendicular to the Z-axis direction. In other words, the third side portion77has a surface substantially parallel to the Z-axis direction. The fourth side portion78has a surface non-parallel to the direction perpendicular to the Z-axis direction. In this example, the fourth side portion78has a surface substantially perpendicular to the direction perpendicular to the Z-axis direction. In other words, the fourth side portion78has a surface substantially parallel to the Z-axis direction. The first side portion75is opposed to the third side portion77. The second side portion76is opposed to the fourth side portion78.

In this specification, the state of being “opposed” includes not only the state of directly facing, but also being indirectly opposed to each other with another element interposed in between.

The cover70has a sound hole71. The sound hole71is provided in the upper portion74and penetrates through the upper portion74. The sound hole71passes sound. For instance, the sound hole71transmits at least the sound outside the microphone package111,112,113to the inside of the microphone package111,112,113(inside of the cover70). For instance, the sound hole71causes at least the sound outside the microphone package111,112,113to flow (travel) into the inside of the microphone package111,112,113(inside of the cover70).

In the microphone package111shown inFIG. 1A, the first side portion75, the second side portion76, the third side portion77, and the fourth side portion78are each formed of a magnetic body.

Alternatively, as in the microphone package112shown inFIG. 2A, the second side portion76aand the fourth side portion78amay be each formed of a non-magnetic body including magnetic particles (magnetic beads). That is, as shown inFIG. 2B, the second side portion76aincludes a non-magnetic body81and magnetic beads83. The fourth side portion78aincludes a non-magnetic body81and magnetic beads83. The non-magnetic body81is formed of e.g. a resin material (nonconductor). The magnetic bead83is made of e.g. nickel (Ni), iron (Fe), cobalt (Co), nickel oxide, iron oxide, cobalt oxide, nickel nitride, iron nitride, or cobalt nitride.

The second side portion76acan be manufactured by e.g. the following method. First, magnetic beads83are mixed into a precured resin material (non-magnetic body81before curing). Then, the precured resin material including the magnetic beads83is poured into a mold and cured. The example of the method for manufacturing the second side portion76ais similarly applied to the method for manufacturing the fourth side portion78a.

The first side portion and the third side portion not shown inFIG. 2Aare similar to the second side portion76aor the fourth side portion78adescribed above.

Alternatively, as in the microphone package113shown inFIGS. 3A and 3B, the first side portion75, the second side portion76, the third side portion77, and the fourth side portion78may be each formed of a non-magnetic body, and then a magnetic body73may be added on the sidewall.

The microphone package113shown inFIGS. 3A and 3Bis now further described.

The cover70includes a magnetic body73. The magnetic body73is provided on the first side portion75, the second side portion76, the third side portion77, and the fourth side portion78. The magnetic body73is made of a magnetic body. The magnetic body73has a magnetic layer. The method for forming a magnetic body73on the side portion (first side portion75, second side portion76, third side portion77, and fourth side portion78) of the cover70can be based on e.g. sputtering technique, CVD technique, or electrolytic/electroless plating technique.

The first side portion75, the second side portion76,76a, the third side portion77, and the fourth side portion78,78aare made of a non-magnetic body. The magnetic body73is made of a magnetic body. The material of the magnetic body can be e.g. NiFe alloy, Ni—Fe—X alloy (X being Cu, Cr, Ta, Rh, Pt, or Nb), CoZrNb alloy, and FeAlSi alloy. Alternatively, the material of the magnetic body can be e.g. a ferrite material such as FeO3or Fe2O3.

The resin material can suppress the reflection of sound waves compared with the metal material. That is, the sound wave injected from the sound hole71into the microphone package113is reflected at other than the pressure sensing element40. The sound wave is reflected by fixed end reflection. Thus, the sound wave experiences a phase shift. If the sound wave experiences a phase shift, the sound wave reflected at other than the pressure sensing element40interferes with the sound wave injected from the sound hole71into the microphone package113. Thus, in the cover70, improvement of acoustic performance is expected. In the embodiments, the surface area of the base material (resin material) of the cover70is larger than the surface area of the magnetic body. Thus, further improvement of acoustic performance is expected. The elasticity of the resin material is higher than the elasticity of the metal material. Thus, in the cover70, improvement of mechanical robustness is expected. The shape workability of the resin material is higher than the shape workability of the metal material. Thus, performance improvement of the microphone package111,112,113is expected.

In the microphone package114shown inFIGS. 4A and 4B, a lid body79formed of e.g. metal is provided on the upper portion74of the cover70. In such a case, sound waves transmitted through the upper portion74of the cover70can be suppressed. The hardness of the lid body79is harder than the hardness of the upper portion74formed of a resin material. Thus, the resonance design can be performed more easily by taking into consideration only the sound injected from the sound hole71into the microphone package114. The hardness of the lid body79and the upper portion74can be measured by e.g. at least one of the test methods for Brinell hardness, Vickers hardness, Rockwell hardness, durometer hardness, Barcol hardness, and monotron hardness.

FIG. 5is a block diagram illustrating the main configuration of an electric circuit of the microphone package according to the embodiments.

The integrated circuit60includes a driving circuit61and a signal processing circuit63. The driving circuit61is installed on the first major surface50sof the mounting substrate50. The signal processing circuit63is installed on the first major surface50sof the mounting substrate50. The mounting substrate50is formed like e.g. a rectangular plate. The mounting substrate50includes a wiring pattern. The driving circuit61supplies a prescribed voltage or current to the pressure sensing element40. The signal processing circuit63amplifies the output of the pressure sensing element40.

An external power supply141is connected to the input side of the driving circuit61. When the external power supply141supplies a voltage or current to the driving circuit61, the driving circuit61is operated and generates an electrical signal required to drive the pressure sensing element40. The output side of the driving circuit61is connected to the input side of the pressure sensing element40. When the electrical signal generated by the driving circuit61is inputted to the pressure sensing element40, the pressure sensing element40is driven. When the pressure sensing element40is driven, an electrical signal is outputted to the output side of the pressure sensing element40. The output side of the pressure sensing element40is connected to the input side of the signal processing circuit63. When the signal processing circuit63has processed a sensing signal, an electrical signal is outputted to the output side of the signal processing circuit63. The output side of the signal processing circuit63is connected to an output terminal143. The electrical signal of the signal processing circuit63is outputted through the output terminal143to the outside of the microphone module. The integrated circuit60is provided with a ground145. That is, the integrated circuit60is grounded.

FIGS. 6A to 7Bare schematic views illustrating the influence of the direction of the external magnetic field.

FIGS. 6A and 7Aare schematic perspective views illustrating the case where an external magnetic field with the component perpendicular to the major surface of the magnetic layer acts on the magnetization of the magnetic layer.FIGS. 6B and 7Bare schematic perspective views illustrating the case where an external magnetic field with the component parallel to the major surface of the magnetic layer acts on the magnetization of the magnetic layer.

The pressure sensing element40includes e.g. a spin valve film formed of a stacked film of ultrathin magnetic films. The resistance of the spin valve film is changed by an external magnetic field. The amount of change of the resistance is the MR rate of change. The MR phenomenon results from various physical effects. The MR phenomenon is based on e.g. the giant magnetoresistive (GMR) effect or the tunneling magnetoresistive (TMR) effect.

The spin valve film has a configuration in which at least two ferromagnetic layers are stacked via a spacer layer. The magnetoresistive state of the spin valve film is determined by the relative angle between the magnetization directions of the two ferromagnetic layers. For instance, when the magnetizations of the two ferromagnetic layers are mutually in the parallel state, the spin valve film is in a low resistance state. When the magnetizations are in the antiparallel state, the spin valve film is in a high resistance state. When the angle between the magnetizations of the two ferromagnetic layers is an intermediate angle, an intermediate resistance state is obtained.

Of the at least two magnetic layers, the magnetic layer in which the magnetization is easily rotated is e.g. a magnetization free layer (second magnetic layer)152. The magnetization free layer152has a major surface152a. The magnetic layer in which the magnetization is changed less easily is a reference layer (first magnetic layer)151. The reference layer151has a major surface151a.

The magnetization direction of the magnetic layer is changed also by an external stress. By using this phenomenon, the spin valve film can be used as a strain sensing element or pressure sensing element. The change of the magnetization (second magnetization) of the magnetization free layer152due to strain is based on e.g. the inverse magnetostriction effect.

The magnetostriction effect is the phenomenon in which the strain of a magnetic material is changed when the magnetization of the magnetic material is changed. The magnitude of the strain is changed depending on the magnitude and direction of the magnetization. The magnitude of the strain can be controlled through these parameters of the magnitude and direction of the magnetization. The amount of change of the strain at which the amount of strain is saturated with the increase in the intensity of the applied magnetic field is the magnetostriction constant λs. The magnetostriction constant depends on the intrinsic characteristics of the magnetic material. The magnetostriction constant (λs) indicates the magnitude of the shape change of the magnetic layer subjected to saturated magnetization in a direction under application of an external magnetic field. The length in the state of no external magnetic field is denoted by L. If the length is changed by ΔL under application of an external magnetic field, the magnetostriction constant λs is represented by ΔL/L. This amount of change is changed with the magnitude of the external magnetic field. However, the magnetostriction constant λs is defined by ΔL/L for the state in which the magnetization is saturated under application of a sufficient external magnetic field. In the embodiments, the absolute value of the magnetostriction constant λs is preferably 10−5or more. Then, strain is efficiently produced by stress, and the sensing sensitivity of pressure is enhanced. The absolute value of the magnetostriction constant is e.g. 10−2or less. This value is an upper limit for practical materials causing the magnetostriction effect.

As a phenomenon opposite to the magnetostriction effect, the inverse magnetostriction effect is known. In the inverse magnetostriction effect, when an external stress is applied, the magnetization of the magnetic material is changed. The magnitude of this change depends on the magnitude of the external stress and the magnetostriction constant of the magnetic material. The magnetostriction effect and the inverse magnetostriction effect are physically symmetric to each other. Thus, the magnetostriction constant of the inverse magnetostriction effect is equal to the magnetostriction constant of the magnetostriction effect.

The magnetostriction effect and the inverse magnetostriction effect are associated with a positive magnetostriction constant or a negative magnetostriction constant. These constants depend on the magnetic material. In the case of a material having a positive magnetostriction constant, the magnetization is changed so as to be directed along the direction of application of a tensile strain. In the case of a material having a negative magnetostriction constant, the magnetization is changed so as to be directed along the direction of application of a compressive strain.

By the inverse magnetostriction effect, the magnetization direction of the magnetization free layer152of the spin valve film can be changed. When an external stress is applied, the magnetization direction of the magnetization free layer152is changed by the inverse magnetostriction effect. This causes a difference in the relative magnetization angle between the reference layer151and the magnetization free layer152. Thus, the resistance of the spin valve film is changed. Accordingly, the spin valve film can be used as a strain sensing element.

The strain sensing element is formed on e.g. a “membrane”. The membrane plays a role like an eardrum for converting pressure to strain. The strain sensing element formed on the membrane reads the strain to enable pressure sensing. The membrane is e.g. a monocrystalline Si substrate. Etching is performed from the rear surface of the monocrystalline Si substrate to thin the portion where the strain sensing element is placed. Thus, a diaphragm is formed. The diaphragm is deformed in response to the applied pressure.

For instance, the shape of the first major surface of the diaphragm projected on the X-Y plane can be geometrically isotropic. Then, around the geometric center point, the strain caused by the diaphragm displacement has a fixed value on the X-Y plane. Thus, if the strain sensing element is placed at the geometric center point of the diaphragm, the strain causing the rotation of magnetization is made isotropic. Accordingly, there occurs no rotation of magnetization of the magnetic layer, and there also occurs no change in the resistance of the device. Thus, in the embodiments, preferably, the strain sensing element is not placed at the geometric center point of the diaphragm. For instance, if the shape of the diaphragm projected on the X-Y plane is circular, the maximum anisotropic strain occurs near the outer periphery of the circular shape by the diaphragm displacement. Thus, if the strain sensing element is placed near the outer periphery of the diaphragm, the sensitivity of the pressure sensing element40is enhanced.

As described with reference toFIG. 5, the pressure sensing element40is connected to the driving circuit61of the integrated circuit60installed on the mounting substrate50. When the electrical signal generated by the driving circuit61is inputted to the pressure sensing element40, the pressure sensing element40is driven.

When the diaphragm is strained in response to the sound pressure of a sound, the pressure sensing element40extracts the change of the voltage in proportion to the change of the resistance of the strain sensing element placed on the diaphragm. The pressure sensing element40is a sound signal change element for converting a sound signal to a voltage signal for output. The output signal of the pressure sensing element40has a relatively low level. Thus, the output side of the pressure sensing element40is connected to an amplifier (e.g., signal processing circuit63). Accordingly, the output signal of the pressure sensing element40representing the sound signal is amplified.

Because the output signal of the pressure sensing element40has a relatively low level, the output signal of the pressure sensing element40is vulnerable to external noise. The resistance of the spin valve film of the pressure sensing element40is changed by an external magnetic field. Thus, the external magnetic field due to e.g. geomagnetism may act as external noise on at least one of the magnetization of the magnetization free layer152and the magnetization (first magnetization) of the reference layer151.

That is, as shown inFIGS. 6A and 6B, in an example of the microphone package111,112,113,114according to the embodiments, the direction of the magnetization of the magnetization free layer152and the direction of the magnetization of the reference layer151are each parallel to the X-Y plane. Namely, the direction of the magnetization of the magnetization free layer152is parallel to the major surface152aof the magnetization free layer152. The direction of the magnetization of the reference layer151is parallel to the major surface151aof the reference layer151. In other words, the direction of the magnetization of the magnetization free layer152is perpendicular to the Z-axis direction (stacking direction). The direction of the magnetization of the reference layer151is perpendicular to the Z-axis direction (stacking direction). The configuration using this state is referred to as “in-plane magnetization scheme”. In the in-plane magnetization scheme, the pressure sensing element40senses pressure change based on the change of the angle between the direction of the magnetization of the reference layer151and the direction of the magnetization of the magnetization free layer152. Thus, the external magnetic field due to e.g. geomagnetism may act as external noise on at least one of the magnetization of the magnetization free layer152and the magnetization of the reference layer151.

On the other hand, as shown inFIGS. 7A and 7B, in an alternative example of the microphone package111,112,113,114according to the embodiments, the direction of the magnetization of the magnetization free layer152and the direction of the magnetization of the reference layer151are each perpendicular to the X-Y plane. Namely, the direction of the magnetization of the magnetization free layer152is perpendicular to the major surface152aof the magnetization free layer152. The direction of the magnetization of the reference layer151is perpendicular to the major surface151aof the reference layer151. In other words, the direction of the magnetization of the magnetization free layer152is parallel to the Z-axis direction (stacking direction). The direction of the magnetization of the reference layer151is parallel to the Z-axis direction (stacking direction). The configuration using this state is referred to as “perpendicular magnetization scheme”. In the perpendicular magnetization scheme, the pressure sensing element40senses pressure change based on the change of the angle between the direction of the magnetization of the reference layer151and the direction of the magnetization of the magnetization free layer152. Thus, the external magnetic field due to e.g. geomagnetism may act as external noise on at least one of the magnetization of the magnetization free layer152and the magnetization of the reference layer151.

As shown inFIGS. 6A and 7A, the first external magnetic field161with the component perpendicular to the major surface152aof the magnetization free layer152does not act on the magnetization of the magnetization free layer152as a force for rotating the magnetization of the magnetization free layer152.

On the other hand, as shown inFIGS. 6B and 7B, the second external magnetic field162with the component parallel to the major surface152aof the magnetization free layer152acts on the magnetization of the magnetization free layer152as a force for rotating the magnetization of the magnetization free layer152. Then, the resistance of the spin valve film may be changed. Thus, the external magnetic field may appear as external noise in the output signal of the pressure sensing element40. Here, for instance, the third external magnetic field163and the fourth external magnetic field164shown inFIG. 6Bare not parallel to the magnetization of the magnetization free layer152, but have a component parallel to the major surface152aof the magnetization free layer152. Thus, the third external magnetic field163and the fourth external magnetic field164act on the magnetization of the magnetization free layer152as a force for rotating the magnetization of the magnetization free layer152. For instance, the fifth external magnetic field165and the sixth external magnetic field166shown inFIG. 7B, like the second external magnetic field162, act on the magnetization of the magnetization free layer152as a force for rotating the magnetization of the magnetization free layer152.

In contrast, in the microphone package111shown inFIGS. 1A and 1B, the first side portion75, the second side portion76, the third side portion77, and the fourth side portion78are each formed of a magnetic body. In the microphone package112shown inFIGS. 2A and 2B, the first side portion, the second side portion76a, the third side portion, and the fourth side portion78aare each formed of a non-magnetic body81including magnetic beads83. In the microphone package113shown inFIGS. 3A and 3B, a magnetic body73is provided on the first side portion75, the second side portion76, the third side portion77, and the fourth side portion78. The magnetic body73forms a magnetic closed circuit. The magnetic body73may have e.g. a slit as long as the magnetic field is continuous.

The first side portion75, the second side portion76,76a, the third side portion77, and the fourth side portion78,78aare each non-parallel to the major surface152aof the magnetization free layer152. Alternatively, the absolute value of the angle between the major surface152aof the magnetization free layer152and each of the plane including the first side portion75, the plane including the second side portion76,76a, the plane including the third side portion77, and the plane including the fourth side portion78,78ais 45 degrees or more. Alternatively, the absolute value of the angle between the major surface152aof the magnetization free layer152and each of the plane including the first side portion75, the plane including the second side portion76,76a, the plane including the third side portion77, and the plane including the fourth side portion78,78ais 85 degrees or more.

In other words, the first side portion75, the second side portion76,76a, the third side portion77, and the fourth side portion78,78aare non-parallel to the direction perpendicular to the stacking direction. Alternatively, the absolute value of the angle between the stacking direction and each of the plane including the first side portion75, the plane including the second side portion76,76a, the plane including the third side portion77, and the plane including the fourth side portion78,78ais less than 45 degrees. Alternatively, the absolute value of the angle between the stacking direction and each of the plane including the first side portion75, the plane including the second side portion76,76a, the plane including the third side portion77, and the plane including the fourth side portion78,78ais 5 degrees or less.

That is, the first side portion75, the second side portion76,76a, the third side portion77, and the fourth side portion78,78aare placed depending on the direction of the magnetization of the reference layer151and the direction of the magnetization of the magnetization free layer152. Specifically, in the case of the in-plane magnetization scheme, the first side portion75, the second side portion76,76a, the third side portion77, and the fourth side portion78,78aeach have a surface substantially perpendicular to the direction of the magnetization of the reference layer151and the direction of the magnetization of the magnetization free layer152. In the case of the perpendicular magnetization scheme, the first side portion75, the second side portion76,76a, the third side portion77, and the fourth side portion78,78aeach have a surface substantially parallel to the direction of the magnetization of the reference layer151and the direction of the magnetization of the magnetization free layer152.

In the microphone package111shown inFIGS. 1A and 1B, when the second external magnetic field162with the component parallel to the major surface152aof the magnetization free layer152is applied, the magnetic flux passes through the magnetic closed circuit formed of the side portion formed of a magnetic body, the side portion being the side portion of the cover70. In the microphone package112shown inFIG. 2A, when the second external magnetic field162with the component parallel to the major surface152aof the magnetization free layer152is applied, the magnetic flux passes through the magnetic closed circuit formed of the side portion including magnetic beads83, the side portion being the side portion of the cover70. In the microphone package113shown inFIGS. 3A and 3B, when the second external magnetic field162with the component parallel to the major surface152aof the magnetization free layer152is applied, the magnetic flux passes through the magnetic closed circuit formed of the magnetic body73. In other words, the magnetic flux of the second external magnetic field162passes through at least one of the magnetic body73provided on the first side portion75, the magnetic body73provided on the second side portion76, the magnetic body73provided on the third side portion77, and the magnetic body73provided on the fourth side portion78.

Then, the magnetic flux of the second external magnetic field162does not penetrate into the cover70. Thus, the side portion of the cover70blocks the second external magnetic field162with the component parallel to the major surface152aof the magnetization free layer152from penetrating into the cover70. Alternatively, the magnetic body73blocks the second external magnetic field162with the component parallel to the major surface152aof the magnetization free layer152from penetrating into the cover70. The pressure sensing element40inside the cover70is not exposed to the second external magnetic field162with the component parallel to the major surface152aof the magnetization free layer152. This can suppress the external magnetic field acting as external noise on the magnetization of the magnetization free layer152. That is, the rotation of the magnetization direction of the magnetization free layer152by the external magnetic field can be suppressed. Thus, a sound signal change element having relatively high SN ratio can be obtained.

As shown inFIG. 1B, the distance (height of the film30) between the first major surface50sand the upper surface of the film30is denoted by D11. The distance (height of the cover70) between the first major surface50sand the upper surface of the cover70is denoted by D12. The distance between the inner wall of the side portion (the second side portion76in the example ofFIGS. 1A and 1B) of the cover70and the end portion of the device25is denoted by D13. Then, if D13<|D12−D11|/tan 45°=|D12−D11| is satisfied, penetration of the second external magnetic field162into the cover70can be blocked more effectively. That is, the blocking effect is more significant when the distance between the inner wall of the side portion of the cover70and the end portion of the device25is smaller than the absolute value of the difference between the distance (height of the cover70) between the first major surface50sand the upper surface of the cover70and the distance (height of the film30) between the first major surface50sand the upper surface of the film30.

Here, the value “45°” refers to the angle at which the ratio of the component perpendicular to the inner wall or outer wall of the side portion (the second side portion76in the example ofFIGS. 1A and 1B) of the cover70versus the component parallel to the inner wall or outer wall of the side portion (the second side portion76in the example ofFIGS. 1A and 1B) of the cover is 1:1.

The integrated circuit60is spaced from the pressure sensing element40in the X-axis direction. Thus, the pressure sensing element40is placed in a region having a length of approximately half the length of the mounting substrate50in the X-axis direction.

For instance, in a capacitance microphone such as a condenser microphone, electromagnetic waves act as noise. Thus, the microphone package (e.g., the base material of the cover70) is formed of metal. In contrast, in the pressure sensing element40according to the embodiments, electromagnetic waves do not act as noise. Thus, the base material of the cover70does not need to be formed of metal. The base material of the cover70can be formed of a resin material. Thus, as described with reference toFIGS. 1A and 1B, in the cover70, improvement of acoustic performance is expected. In the cover70, improvement of mechanical robustness is expected. Performance improvement of the microphone package111,112,113is expected.

As described above, a magnetic body (including magnetic beads) is placed on the side portion of the cover70provided depending on the direction of the magnetization of the reference layer151in the cover70and the direction of the magnetization of the magnetization free layer152in the cover70. Thus, penetration of the second external magnetic field162into the cover70can be blocked more effectively. On the other hand, the remaining portion of the cover70can be made of a material advantageous to acoustic performance.

FIGS. 8A to 8Care schematic views illustrating the configuration of the pressure sensing element of the embodiments.FIG. 8Cis a transparent plan view.FIG. 8Ais a sectional view taken along line B1-B2ofFIG. 8C.FIG. 8Bis a sectional view taken along line C1-C2ofFIG. 8C.

As shown inFIGS. 8A to 8C, the pressure sensing element40includes a film30and a device25.

The film30has a first major surface30s. The first major surface30shas a first edge portion30a, a second edge portion30b, and an inside portion30c. The second edge portion30bis spaced from the first edge portion30a. The inside portion30cis located e.g. between the first edge portion30aand the second edge portion30b.

For instance, the pressure sensing element40includes a membrane34. The membrane34corresponds to the film30. A recess30ois provided in part of the inside of the membrane34. The shape of the recess30oprojected on the X-Y plane is e.g. a circle (including a flattened circle), or a polygon. The recess30oof the membrane34(the thin portion of the membrane34) constitutes the inside portion30c. The periphery of the inside portion30c(e.g., the portion of the membrane34thicker than the recess30o) constitutes outside portions. One of the outside portions constitutes the first edge portion30a. Another of the outside portions constitutes the second edge portion30b. The membrane34is made of e.g. silicon. However, the embodiments are not limited thereto, but the material of the membrane34is arbitrary.

In this example, the thickness of the outside portion of the membrane34is different from the thickness of the inside portion30c. The embodiments are not limited thereto, but these thicknesses may be equal to each other. In this example, the shape of the membrane34is rectangular. However, the shape is arbitrary.

The device25is provided on the first major surface30s. The device25includes a first electrode10, a second electrode20, a first magnetic layer11, a second magnetic layer12, and a non-magnetic layer13.

The first electrode10has a first portion10aand a second portion10b. The first portion10ais opposed to the first edge portion30a. The second portion10bis opposed to the inside portion30c.

The second electrode20has a third portion20aand a fourth portion20b. The third portion20ais opposed to the inside portion30c. The fourth portion20bis opposed to the second edge portion30b. The fourth portion20bdoes not overlap the first electrode10as projected on the X-Y plane (the plane parallel to the first major surface30s).

The first magnetic layer11is provided between the second portion10band the third portion20a.

The second magnetic layer12is provided between the first magnetic layer11and the third portion20a.

The non-magnetic layer13is provided between the first magnetic layer11and the second magnetic layer12.

The first magnetic layer11, the non-magnetic layer13, and the second magnetic layer12are stacked along the Z-axis direction (stacking direction).

In this specification, the state of being “stacked” includes not only the state of being stacked in contact with each other, but also the state of being stacked with another element interposed in between.

The first magnetic layer11, the non-magnetic layer13, and the second magnetic layer12constitute a strain sensing element15. That is, the device25includes the first electrode10, the second electrode20, and the strain sensing element15. In the pressure sensing element40, in response to the strain of the film30, the angle between the direction of the magnetization of the first magnetic layer11and the direction of the magnetization of the second magnetic layer12is changed. An example of the configuration and characteristics of the strain sensing element15will be described later.

An insulating layer14embedding the strain sensing element15is provided. The insulating layer14is made of e.g. SiO2or Al2O3.

In this example, on the inside portion30c, the second portion10bof the first electrode10, the first magnetic layer11, the non-magnetic layer13, the second magnetic layer12, and the third portion20aof the second electrode20are provided in this order. That is, the second portion10bis placed between the third portion20aand the inside portion30c. However, the embodiments are not limited thereto. The third portion20amay be placed between the second portion10band the inside portion30c.

The first magnetic layer11has a first magnetization. In the embodiments, the direction of the first magnetization is parallel to the X-Y plane. The second magnetic layer12has a second magnetization. In the embodiments, the direction of the second magnetization is parallel to the X-Y plane. In other words, the direction of the first magnetization is perpendicular to the Z-axis direction (stacking direction). The direction of the second magnetization is perpendicular to the Z-axis direction (stacking direction). As described above with reference toFIGS. 6A and 6B, the configuration using this state is referred to as “in-plane magnetization scheme”. In the in-plane magnetization scheme, the first magnetic layer11is made of an in-plane magnetization film. In the in-plane magnetization scheme, the second magnetic layer12is made of an in-plane magnetization film.

For instance, the first magnetic layer11functions as a reference layer. The second magnetic layer12functions as a free layer. In the free layer, the direction of the magnetization is easily changed by the external magnetic field. The direction of the magnetization of the reference layer is changed less easily than e.g. the direction of the magnetization of the free layer. The reference layer is e.g. a pin layer. Alternatively, both the first magnetic layer11and the second magnetic layer12may be free layers.

For instance, when a stress is applied to a ferromagnetic body, the inverse magnetostriction effect occurs in the ferromagnetic body. By the stress applied to the strain sensing element15, the direction of the magnetization of the magnetic layer is changed based on the inverse magnetostriction effect. The angle between the direction of the magnetization of the first magnetic layer11and the direction of the magnetization of the second magnetic layer12is changed. Thus, for instance, by the MR (magnetoresistive) effect, the electrical resistance of the strain sensing element15is changed.

In the pressure sensing element40, by the stress applied to the pressure sensing element40, a displacement occurs in the film30. Thus, a stress is applied to the strain sensing element15, and the electrical resistance of the strain sensing element15is changed. The pressure sensing element40senses the stress using this effect.

FIGS. 9A to 9Dare schematic perspective views illustrating a configuration and the characteristics of the pressure sensing element according to the embodiments.

FIG. 9Aillustrates the configuration of the device25.FIG. 9Billustrates the state of the strain sensing element15under no application of stress.FIG. 9Cillustrates the state of the strain sensing element15having a positive magnetostriction constant under application of a tensile stress.FIG. 9Dillustrates the state of the strain sensing element15having a negative magnetostriction constant under application of a tensile stress.

As shown inFIG. 9A, on the first electrode10, the first magnetic layer11(reference layer), the non-magnetic layer13, the second magnetic layer12(magnetization free layer), and the second electrode20are stacked in this order. This example is of the in-plane magnetization scheme. The direction of the magnetization of the first magnetic layer11(as well as the direction of the magnetization of the second magnetic layer12) is e.g. substantially parallel to the X-Y plane. The embodiments are not limited thereto. The angle between the direction of the magnetization of the first magnetic layer11and the direction parallel to the X-Y plane (first major surface30s) is less than 45°. In the case where the magnetostriction constant of the magnetic layer is positive, the magnetization easy axis of the magnetic layer is parallel to the direction of application of the tensile stress. In the case where the magnetostriction constant of the magnetic layer is negative, the magnetization easy axis of the magnetic layer is perpendicular to the direction of application of the tensile stress.

As shown inFIG. 9B, under no application of stress, the direction of the magnetization of the second magnetic layer12(magnetization free layer) is e.g. parallel to the direction of the magnetization of the first magnetic layer11(reference layer). In this example, the direction of the magnetization is directed along the Y-axis direction.

As shown inFIG. 9C, for instance, a tensile stress Fs is applied along the X-axis direction. Then, by the inverse magnetostriction effect with a positive magnetostriction constant, the magnetization of the second magnetic layer12is rotated toward the X-axis direction. If the magnetization of the first magnetic layer11is fixed, the relative angle between the direction of the magnetization of the second magnetic layer12and the direction of the magnetization of the first magnetic layer11is changed. In response to the change of the relative angle, the electrical resistance of the strain sensing element15is changed.

As shown inFIG. 9D, for instance, a tensile stress Fs is applied along the Y-axis direction. Then, by the inverse magnetostriction effect with a negative magnetostriction constant, the magnetization of the second magnetic layer12is rotated toward the X-axis direction. Also in this case, by the application of the tensile stress Fs, the relative angle between the direction of the magnetization of the second magnetic layer12and the direction of the magnetization of the first magnetic layer11is changed. In response to the change of the relative angle, the electrical resistance of the strain sensing element15is changed.

FIGS. 10A to 10Dare schematic perspective views illustrating an alternative configuration and the characteristics of the pressure sensing element according to the embodiments.

FIG. 10Aillustrates the configuration of the device25.FIG. 10Billustrates the state of the strain sensing element15under no application of stress.FIG. 10Cillustrates the state of the strain sensing element15having a positive magnetostriction constant under application of a tensile stress.FIG. 10Dillustrates the state of the strain sensing element15having a negative magnetostriction constant under application of a tensile stress.

As shown inFIG. 10A, this example is of the perpendicular magnetization scheme. The direction of the magnetization of the first magnetic layer11(as well as the direction of the magnetization of the second magnetic layer12) is e.g. substantially parallel to the Z-axis direction. The embodiments are not limited thereto. The angle between the direction of the magnetization of the first magnetic layer11and the direction parallel to the X-Y plane (first major surface30s) is greater than 45°.

As shown inFIG. 10B, under no application of stress, the direction of the magnetization of the second magnetic layer12(magnetization free layer) is e.g. parallel to the direction of the magnetization of the first magnetic layer11(reference layer). In this example, the direction of the magnetization is directed along the Y-axis direction.

As shown inFIG. 10C, for instance, a tensile stress Fs is applied along the X-axis direction. Then, by the inverse magnetostriction effect with a positive magnetostriction constant, the magnetization of the second magnetic layer12is rotated toward the X-axis direction. The relative angle between the direction of the magnetization of the second magnetic layer12and the direction of the magnetization of the first magnetic layer11is changed. In response to the change of the relative angle, the electrical resistance of the strain sensing element15is changed.

As shown inFIG. 10D, for instance, a tensile stress Fs is applied along the Y-axis direction. Then, by the inverse magnetostriction effect with a negative magnetostriction constant, the magnetization of the second magnetic layer12is rotated toward the X-axis direction. By the application of the tensile stress Fs, the relative angle between the direction of the magnetization of the second magnetic layer12and the direction of the magnetization of the first magnetic layer11is changed. In response to the change of the relative angle, the electrical resistance of the strain sensing element15is changed.

In the following, in the case of the configuration of the in-plane magnetization scheme, an example of the configuration of the strain sensing element15is described.

For instance, in the case where the first magnetic layer11is a reference layer, the first magnetic layer11is made of e.g. FeCo alloy, CoFeB alloy, or NiFe alloy. The thickness of the first magnetic layer11is e.g. 2 nm (nanometers) or more and 6 nm or less.

The non-magnetic layer13is made of metal or insulator. The metal is e.g. Cu, Au, or Ag. The thickness of the non-magnetic layer13made of metal is e.g. 1 nm or more and 7 nm or less. The insulator is e.g. magnesium oxide (such as MgO), aluminum oxide (such as Al2O3), titanium oxide (such as TiO), or zinc oxide (such as ZnO). The thickness of the non-magnetic layer13made of insulator is e.g. 0.6 nm or more and 2.5 nm or less.

The magnetization direction of at least one magnetic layer of the first magnetic layer11and the second magnetic layer12is changed in response to the stress. The absolute value of the magnetostriction constant of the at least one magnetic layer (the magnetic layer in which the magnetization direction is changed in response to the stress) is set to e.g. 10−5or more. Thus, by the inverse magnetostriction effect, the direction of the magnetization is sufficiently changed in response to the externally applied strain.

For instance, the non-magnetic layer13is made of oxide such as MgO. Then, the magnetic layer on the MgO layer typically has a positive magnetostriction constant. For instance, in the case where the second magnetic layer12is formed on the non-magnetic layer13, a magnetization free layer having a stacked configuration of CoFeB/CoFe/NiFe is used as the second magnetic layer12. If the uppermost NiFe layer is made Ni-rich, the magnetostriction constant of NiFe is made negative and has a large absolute value. In order to suppress cancelation of the positive magnetostriction on the oxide layer, the Ni composition of the uppermost NiFe layer is not made Ni-rich. Specifically, the proportion of Ni in the uppermost NiFe layer is preferably set to less than 80 atomic percent. In the case where the second magnetic layer12is a magnetization free layer, the thickness of the second magnetic layer12is preferably e.g. 1 nm or more and 20 nm or less.

In the case where the second magnetic layer12is a magnetization free layer, the first magnetic layer11may be either a reference layer or a magnetization free layer. In the case where the first magnetic layer11is a reference layer, the direction of the magnetization of the first magnetic layer11is not substantially changed even under application of external strain. The electrical resistance is changed based on the relative magnetization angle between the direction of the magnetization of the first magnetic layer11and the direction of the magnetization of the second magnetic layer12.

In the case where the first magnetic layer11and the second magnetic layer12are both magnetization free layers, for instance, the magnetostriction constant of the first magnetic layer11is different from the magnetostriction constant of the second magnetic layer12.

Irrespective of whether the first magnetic layer11is a reference layer or a magnetization free layer, the thickness of the first magnetic layer11is preferably e.g. 1 nm or more and 20 nm or less.

In the case where the first magnetic layer11is a reference layer, the first magnetic layer11is based on a synthetic AF structure using a stacked structure of antiferromagnetic layer/magnetic layer/Ru layer/magnetic layer. The antiferromagnetic layer is made of e.g. IrMn. In the case where the first magnetic layer11is a reference layer, instead of using an antiferromagnetic layer, the first magnetic layer11may be based on a configuration using a hard film. The hard film is made of e.g. CoPt or FePt.

In the following, in the case of the configuration of the perpendicular magnetization scheme, an example of the configuration of the strain sensing element15is described.

For instance, in the case where the first magnetic layer11is a reference layer, the first magnetic layer11is based on a stacked configuration of e.g. CoFe (2 nm)/CoFeB (1 nm). By the pinning layer, the direction of the magnetization is fixed to the film surface direction.

The non-magnetic layer13can be made of metal or insulator. The metal can be e.g. Cu, Au, or Ag. The thickness of the non-magnetic layer13made of metal is e.g. 1 nm or more and 7 nm or less. The insulator can be e.g. magnesium oxide (such as MgO), aluminum oxide (such as Al2O3), titanium oxide (such as TiO), or zinc oxide (such as ZnO). The thickness of the non-magnetic layer13made of insulator is e.g. 0.6 nm or more and 2.5 nm or less.

In the case where the second magnetic layer12is a magnetization free layer, the second magnetic layer12has a magnetization perpendicular to the film surface. In order to obtain the magnetization direction perpendicular to the film surface, for instance, the second magnetic layer12can be made of e.g. CoFeB (1 nm)/TbFe (3 nm). By using CoFeB at the interface on MgO, the MR ratio can be increased. However, perpendicular magnetic anisotropy is difficult to achieve by a monolayer of CoFeB. Thus, an additional layer exhibiting perpendicular magnetic anisotropy is used. For this function, for instance, a TbFe layer is used. A TbFe layer with Tb being 20 atomic percent or more and 40 atomic percent or less exhibits perpendicular magnetic anisotropy. By using such a stacked film configuration, the direction of the magnetization of the entire magnetization free layer is directed in the direction perpendicular to the film surface due to the effect of the TbFe layer. By the effect of the CoFeB layer at the MgO interface, a large MR rate of change can be maintained. The TbFe layer has a very large positive magnetostriction constant, with the value being approximately +10−4. By this large magnetostriction constant, the magnetostriction constant of the entire magnetization free layer can be easily set to a value as large as +10−6. Furthermore, it is also possible to obtain a magnetostriction constant larger than +10−5.

The TbFe layer can develop two functions: the magnetization direction directed perpendicular to the film surface, and a large magnetostriction constant. While using this material, other elements may be added as needed.

In order to obtain perpendicular magnetic anisotropy, materials other than TbFe may be used. The second magnetic layer12can be made of e.g. CoFeB (1 nm)/(Co (1 nm)/Ni (1 nm))×n (n being 2 or more). The Co/Ni multilayer film develops perpendicular magnetic anisotropy. The thickness of the Co film and the Ni film is approximately 0.5 nm or more and 2 nm or less.

The absolute value of the magnetostriction constant of the entire magnetization free layer is 10−6or more. In order to increase the magnetostriction constant, an additional layer of e.g. FeSiB having a large magnetostriction constant is used. FeSiB exhibits a large positive magnetostriction constant (approximately +10−4). Thus, the magnetization free layer as a whole achieves a large positive magnetostriction constant. It is also possible to apply a configuration such as CoFeB (1 nm)/(Co (1 nm)/Ni (1 nm))×n/FeSiB (2 nm).

The second magnetic layer12can be based on e.g. a stacked film of Mp and Ml. Mp is a magnetic layer exhibiting perpendicular magnetic anisotropy, and Ml is a magnetic layer exhibiting a large magnetostriction constant. The second magnetic layer12can be made of a multilayer film such as Mp/Ml, Ml/Mp, Mp/x/Ml, Ml/x/Mp, x/Ml/Mp, Ml/Mp/x, x/Mp/Ml, or Mp/Ml/x. The additional layer x can be used as needed when the function obtained by Ml and Mp alone is insufficient. For instance, in order to increase the MR rate of change, the x layer is provided at the interface with the non-magnetic layer13. This x layer can be e.g. a CoFeB layer or CoFe layer.

The magnetic layer Mp can be made of CoPt—SiO2granular, FePt, CoPt, Co/Pd multilayer film, Co/Pt multilaver film, or Co/Ir multilayer film. TbFe and Co/Ni multilayer film can be regarded as materials having the function of Mp. The number of layers in the multilayer film is e.g. 2 or more and 10 or less.

The magnetic layer Ml can be made of Ni, Ni alloy (alloy containing a large amount of Ni such as Ni95Fe5), SmFe, DyFe, or a magnetic oxide material containing Co, Fe, or Ni. TbFe and Co/Ni multilayer film can be used for a layer having not only the function of Mp but also the function of Ml. It is also possible to use an amorphous alloy layer based on FeSiB. Ni, Ni-rich alloy, and SmFe exhibit a large negative magnetostriction constant. In this case, the magnetization free layer is caused to function so that the signature of the magnetostriction of the entire magnetization free layer is negative. Oxide magnetic materials containing Fe, Co, or Ni such as CoOx, FeOx, or NiOx(0<x<0.8) exhibit a large positive magnetostriction constant. In this case, the signature of the magnetostriction of the entire magnetization free layer is positive.

In order to develop magnetic anisotropy perpendicular to the film surface, the Mp materials as described above can be used. However, as the case may be, the CoFeB layer regarded as the aforementioned x layer used at the interface with the non-magnetic layer can be caused to function as Mp. In this case, the thickness of the CoFeB layer is made thinner than 1 nm. Then, it is also possible to develop magnetic anisotropy perpendicular to the film surface.

In both cases of the in-plane magnetization scheme and the perpendicular magnetization scheme, the first electrode10and the second electrode20are made of e.g. a non-magnetic body such as Au, Cu, Ta, or Al. The first electrode10and the second electrode20are made of a soft magnetic material. This can reduce external magnetic noise affecting the strain sensing element15. The soft magnetic material is e.g. permalloy (NiFe alloy) or silicon steel (FeSi alloy).

The periphery of the strain sensing element15is surrounded with the insulating layer14. The insulating layer14is made of e.g. aluminum oxide (e.g., Al2O3) or silicon oxide (e.g., SiO2). The insulating layer14electrically insulates between the first electrode10and the second electrode20.

For instance, in the case where the non-magnetic layer13is made of metal, the GMR effect is developed. In the case where the non-magnetic layer13is made of insulator, the TMR effect is developed. The strain sensing element15is based on e.g. the CPP (current perpendicular to plane)-GMR effect in which the current is passed along the stacking direction.

FIGS. 11A to 11Care schematic views illustrating a configuration of the mounting substrate of the embodiments.

FIG. 11Ais a schematic plan view of the first major surface50s.FIG. 11Bis a schematic plan view of the second major surface50b.FIG. 11Cis a sectional view taken along line D1-D2ofFIG. 11A.

As shown inFIGS. 11A and 11B, the mounting substrate50includes an external power supply electrode pad51, an output terminal electrode pad53, and a ground electrode pad55. As shown inFIG. 11C, by the application of surface mounting technology, the output terminal electrode pad53is provided from the first major surface50sthrough a through hole to the second major surface50b. By the output terminal electrode pad53, the first major surface50sis electrically connected to the second major surface50b. This also applies to the external power supply electrode pad51and the ground electrode pad55.

The driving circuit61includes a driving circuit input electrode pad61aand a driving circuit output electrode pad61b. The signal processing circuit63includes a signal processing circuit input electrode pad63aand a signal processing circuit output electrode pad63b. The integrated circuit60includes an integrated circuit output electrode pad65. The pressure sensing element40includes a pressure sensing element input electrode pad40aand a pressure sensing element output electrode pad40b.

The external power supply141(seeFIG. 5) is electrically connected to the external power supply electrode pad51. The external power supply electrode pad51is electrically connected to the driving circuit input electrode pad61aby a first wire57a. The driving circuit output electrode pad61bis electrically connected to the pressure sensing element input electrode pad40aby a second wire57b. The pressure sensing element output electrode pad40bis electrically connected to the signal processing circuit input electrode pad63aby a third wire57c. The signal processing circuit output electrode pad63bis electrically connected to the output terminal electrode pad53by a fourth wire57d. The output terminal electrode pad53is electrically connected to the output terminal143(seeFIG. 5). The integrated circuit output electrode pad65is electrically connected to the ground electrode pad55by a fifth wire57e. The integrated circuit60is grounded via the integrated circuit output electrode pad65, the fifth wire57e, and the ground electrode pad55.

FIGS. 12A, 12B, and 13are schematic views illustrating an alternative configuration of the mounting substrate of the embodiments.

FIG. 12Ais a schematic plan view of the first major surface50s.FIG. 12Bis a sectional view taken along line F1-F2ofFIG. 12A.FIG. 13is a schematic enlarged view of the pressure sensing element40. For convenience of description, inFIG. 12B, the cover70is not shown.

In the alternative configuration of the mounting substrate50shown inFIGS. 12A, 12B, and 13, the driving circuit61is provided on the pressure sensing element40. The signal processing circuit63is provided on the pressure sensing element40. In other words, the driving circuit61and the signal processing circuit63are each incorporated on the pressure sensing element40.

On the pressure sensing element40, a third electrode68is provided. The third electrode68has a fifth portion68aand a sixth portion68b. The external power supply electrode pad51is electrically connected to the fifth portion68aof the third electrode68by a sixth wire57f. The sixth portion68bof the third electrode68is electrically connected to the output terminal electrode pad53by a seventh wire57g.

In the case where the membrane34(see, e.g.,FIGS. 8A to 8C) is formed of silicon, the region of the pressure sensing element40other than the strain sensing element15is made of silicon. Thus, the driving circuit61and the signal processing circuit63can be formed of silicon transistors by using the semiconductor formation method.

The embodiments of the invention have been described above with reference to examples. However, the invention is not limited to these examples. For instance, any specific configurations of various components such as the cover and magnetic body included in the microphone package, and the electrode, magnetic layer, non-magnetic layer, strain sensing element, device, membrane, and mounting substrate included in the pressure sensing element are encompassed within the scope of the invention as long as those skilled in the art can similarly practice the invention and achieve similar effects by suitably selecting such configurations from conventionally known ones.

Further, any two or more components of the specific examples may be combined within the extent of technical feasibility and are included in the scope of the embodiments to the extent that the spirit of the embodiments is included.