CN113630705A

CN113630705A - Micro-electro-mechanical system microphone, microphone monomer and electronic equipment

Info

Publication number: CN113630705A
Application number: CN202110875312.7A
Authority: CN
Inventors: 邹泉波; 丁凯文
Original assignee: Goertek Microelectronics Inc
Current assignee: Goertek Microelectronics Inc
Priority date: 2021-07-30
Filing date: 2021-07-30
Publication date: 2021-11-09
Anticipated expiration: 2041-07-30
Also published as: CN113630705B

Abstract

Disclosed herein are a micro electro mechanical system microphone, a microphone unit, and an electronic apparatus. The mems microphone includes: a movable member on which a first current line segment is provided; and a second support, wherein a second current line segment is disposed on the second support, the first current line segment includes a first magnetic resistance, the second current line segment includes a second magnetic resistance, wherein current directions in the first magnetic resistance and the second magnetic resistance are the same, wherein, in a case where the first magnetic resistance and the second magnetic resistance are coplanar, a smaller one of a width of the first magnetic resistance and a width of the second magnetic resistance is CD1, a minimum spacing between the first magnetic resistance and the second magnetic resistance is CD2, and a relationship of CD1 and CD2 is as follows: CD2 is less than or equal to 3 multiplied by CD 1.

Description

Micro-electro-mechanical system microphone, microphone monomer and electronic equipment

Technical Field

Embodiments disclosed herein relate to the field of Micro Electro Mechanical System (MEMS) microphone technology, and more particularly, to a MEMS microphone, a microphone unit, and an electronic device.

Background

As technology has evolved, technicians have begun to apply magneto-resistance to mems microphones. The magneto-resistance may include, for example, giant magneto-resistance (GMR), tunneling magneto-resistance (TMR), and the like. The skilled person expects that miniaturised high performance/reliable products can be manufactured using magneto-resistance.

The properties of magnetic materials are complex. Magneto-resistive materials in practical use often encounter practical problems that cannot be predicted in theoretical studies. In general, it is difficult to determine the cause of a problem with a magnetic element, and therefore it is also difficult to find a solution to this problem.

Disclosure of Invention

It is an object of the present disclosure to provide a new solution for a mems microphone.

According to a first aspect of the present disclosure, there is provided a mems microphone comprising: a first support member; a movable member provided on the first support, wherein a first current line segment is provided on the movable member; and a second support, wherein a second current line segment is disposed on the second support, wherein the movable member is movable with a change in sound pressure such that the first current line segment moves with respect to the second current line segment, wherein the first current line segment includes a first magnetic resistance and the second current line segment includes a second magnetic resistance, and wherein, when the first current line segment moves with respect to the second current line segment, a magnetic field generated by a current in the first current line segment can change a resistance value of the second magnetic resistance, and a magnetic field generated by a current in the second current line segment can change a resistance value of the first magnetic resistance to generate a corresponding sound signal by a change in the resistance values of the first magnetic resistance and the second magnetic resistance, wherein current directions in the first magnetic resistance and the second magnetic resistance are the same, wherein, in a case where the first magnetic resistance and the second magnetic resistance are coplanar, a smaller one of the widths of the first magnetic resistance and the second magnetic resistance is CD1, the minimum spacing between the first magnetoresistance and the second magnetoresistance is CD2, and the relationship between CD1 and CD2 is as follows: CD2 is less than or equal to 3 multiplied by CD 1.

According to a second aspect of the present disclosure, there is provided a microphone cell comprising a cell housing, a mems microphone according to an embodiment, and an integrated circuit chip, wherein the mems microphone and the integrated circuit chip are disposed in the cell housing.

According to a third aspect of the present disclosure, there is provided an electronic device including the microphone monomer according to the embodiment.

According to the embodiment of the disclosure, the sensitivity of the micro-electromechanical system microphone can be improved.

Other features of the present disclosure and advantages thereof will become apparent from the following detailed description of exemplary embodiments thereof, which proceeds with reference to the accompanying drawings.

Drawings

The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate embodiments of the disclosure and together with the description, serve to explain the principles of the disclosure.

FIG. 1 is a schematic top view of a MEMS microphone according to one embodiment of the present disclosure.

Fig. 2 is a sectional view taken along a broken line a-a' in fig. 1.

FIG. 3 is a schematic circuit diagram of a Wheatstone bridge including the magneto-resistance in the embodiment of FIG. 1.

Fig. 4-6 are schematic diagrams illustrating principles according to embodiments of the present disclosure.

Fig. 7 is a schematic graph illustrating the effect according to an embodiment of the present disclosure.

Fig. 8 is a schematic diagram of a microphone cell according to one embodiment of the present disclosure.

Fig. 9 is a schematic diagram of an electronic device according to one embodiment of the present disclosure.

Detailed Description

Various exemplary embodiments of the present disclosure will now be described in detail with reference to the accompanying drawings. It should be noted that: the relative arrangement of the components and steps, the numerical expressions, and numerical values set forth in these embodiments do not limit the scope of the present disclosure unless specifically stated otherwise.

The following description of at least one exemplary embodiment is merely illustrative in nature and is in no way intended to limit the disclosure, its application, or uses.

Techniques, methods, and apparatus known to those of ordinary skill in the relevant art may not be discussed in detail but are intended to be part of the specification where appropriate.

In all examples shown and discussed herein, any particular value should be construed as merely illustrative, and not limiting. Thus, other examples of the exemplary embodiments may have different values.

It should be noted that: like reference numbers and letters refer to like items in the following figures, and thus, once an item is defined in one figure, further discussion thereof is not required in subsequent figures.

In the previous studies by the inventors, the inventors set two parallel magnetoresistances. When current flows through the magneto-resistances, the currents in the two magneto-resistances generate magnetic fields, respectively. When the relative positions of the two magnetoresistors are changed, the magnetic field applied by one magnetoresistor to the other magnetoresistor is also changed, thereby changing the resistance value of the other magnetoresistor. By detecting this resistance change, the magnitude of the relative position change can be detected.

The performance of mems microphones including magnetic resistance sometimes varies widely during actual manufacturing. Due to the complexity of the magnetic material itself, it is difficult to determine the reason for the low yield of mems microphones. For example, it is difficult to tell whether such a difference in performance is due to a difference in the material itself? Is it due to a difference in wiring pattern? Is it due to the difference in reluctance shape?

The inventor herein has found through continuous experiments that in such a solution of parallel magnetoresistances, the sensing performance of the magnetoresistances is related to the distance between the parallel magnetoresistances. In addition, the inventors have found that the detection performance of the magnetic resistance is also related to the direction of the current. Thus, the inventors contemplate that for a device of this size of mems microphone, currents in the same direction in the two magnetoresistances may be attracted to each other and brought into close proximity to each other at a certain distance, thereby enhancing the strength of the magnetic field generated by one magnetoresistance at the other.

In order to determine the above-mentioned distance, the inventors have found, after conducting a large number of experiments, that the above-mentioned phenomenon is related to the relationship between the width of the magneto-resistance and the pitch of the magneto-resistance. When the pitch of the magnetic resistance is less than three times the width of the magnetic resistance, the sensitivity of the magnetic resistance for detection is significantly increased. In particular, when the pitch of the magneto-resistance is smaller than the width of the magneto-resistance, the improvement of the performance is more remarkable.

The principle of the above assumption will be described with reference to fig. 4 to 7.

As shown in fig. 4, the magnetic resistance 23 is provided on the support 21, and the magnetic resistance 24 is provided on the support 22. Assuming that the widths of the

magnetoresistors

23, 24 are both CD1, the spacing between the

magnetoresistors

23, 24 is CD 2. The fabrication pitch FP of the magneto-

resistors

23, 24 can generally be considered to be the distance from the centerline of the magneto-resistor 23 to the centerline of the magneto-resistor 24. Here, FP is CD1+ CD 2.

Fig. 5 shows the situation in which the current directions in the

magnetic resistances

23, 24 are opposite. As shown in fig. 5, the direction of current in reluctance 23 is outward in the direction perpendicular to the paper, and the direction of current in reluctance 24 is inward in the direction perpendicular to the paper. Under the influence of the mutually excited magnetic fields, a significant current repulsion effect is produced in the

magnetoresistances

23, 24. This results in an increase in the spacing of the main current regions in the magneto-

resistances

23, 24, i.e. the effective spacing EP. As shown in fig. 5, the effective spacing EP between the

magnetoresistors

23, 24 is greater than the fabrication spacing FP. Here, the effective pitch EP tends to be CD1+ CD2+ CD 1.

As shown in fig. 6, the directions of currents in the

magnetic resistances

23, 24 are the same, and they are both in the direction perpendicular to the paper surface and out. Because the

magnetoresistors

23, 24 are relatively close together, a significant current crowding/concentration effect is produced in the

magnetoresistors

23, 24 under the influence of the mutually excited magnetic fields. This results in a reduction of the spacing of the main current regions in the magneto-

resistances

23, 24, i.e. the effective spacing EP. As shown in fig. 6, the effective spacing EP between the

magnetoresistors

23, 24 is smaller than the fabrication spacing FP. Here, the effective pitch EP tends toward CD 2. As the effective spacing EP is reduced, the magnetic field strength generated by each of the

magnetoresistances

23, 24 at the other is increased, thereby improving the sensitivity of the detection of the

magnetoresistances

23, 24.

In addition, the inventor experimentally found that, for a device with the size of the mems microphone, in the case that CD2 is equal to or less than 3 times CD1, the influence of the current crowding/concentration effect on the sensitivity of the magnetoresistance detection is large.

Fig. 7 shows a variation curve of the magnetoresistance sensitivity when the current directions are different. In fig. 7, the solid line curve located on the upper side represents an exemplary test result of tunneling magnetoresistance, and the dashed line curve located on the lower side represents an exemplary test result of giant magnetoresistance. In the experiment, the fabrication gap FP between the two magnetoresistors remains unchanged. In fig. 7, open dots a and D represent theoretical sensitivities based on the production gap. As shown by the solid line curve in fig. 7, when the current directions in the two magnetoresistances are the same, the value of the sensitivity is located at point B; when the current directions in the two magnetoresistances are opposite, the value of the sensitivity is located at point C. As shown by the dashed curve in fig. 7, when the current directions in the two magnetoresistances are the same, the value of the sensitivity is located at point E; when the directions of the currents in the two magnetoresistances are opposite, the value of the sensitivity is located at point F. It is apparent that the sensitivity value of the B spot is larger than that of the C spot, and that the sensitivity value of the E spot is larger than that of the F spot. It is assumed that the widths of the two magnetoresistances and the spacing between them are both CD. Then, the effective pitch when the directions of currents in the two magnetoresistors are opposite may be at most 3 times the effective pitch when the directions of currents in the two magnetoresistors are the same. Therefore, by setting the current directions in the two magnetoresistances to be the same, the sensitivity of the mems microphone can be effectively improved.

Based on the above assumptions of the inventors and experimental results, the inventors propose the following examples.

FIG. 1 illustrates a top view of a MEMS microphone in accordance with one embodiment. The top view shown in FIG. 1 is in the XY plane, where the pinning direction Pin of the magnetoresistance is the positive X direction. Fig. 2 shows a cross-sectional view along the dashed line a-a' in fig. 1. The cross-sectional view shown in FIG. 2 is in the XZ plane, where the pinning direction Pin of the magnetoresistance is the positive X direction. As shown in fig. 1 and 2, the mems microphone includes: a first support 7; a movable part 1 provided on the first support 7, wherein a first current line segment 3a is provided on the movable part; and a

second support

2, 8, wherein a second current line section 3b is provided on the second support 2. The movable part 1 is, for example, a diaphragm, which is movable in response to a change in sound pressure so that the first current line segment 3a is moved relative to the second current line segment 3 b. As shown in fig. 2, the movable member 1 moves in the direction indicated by the broken line a. When the movable part 1 moves, it deviates from the rest operating position (or default operating position) indicated by the dashed line O.

As shown in fig. 1 and 2, the movable member is a first suspension arm 1, and a first current line segment 3a is located at an end of the first suspension arm 1. The

second support

2, 8 comprises a second cantilever 2, the second cantilever 2 having a smaller length than the first cantilever 1, the second current line segment 3b being located at the end of the second cantilever 2, and the end of the second cantilever 2 being adjacent to the end of the first cantilever 1. The

second support

2, 8 further comprises a support portion 8 supporting the second boom 2. Due to the short length of the second boom 2, the second boom 2 can be considered as fixed in practice. Furthermore, in some embodiments, the second cantilever may be omitted and the second current line segment 3b may be provided directly on the support portion 8. However, by providing the second current line segment 3b using the second suspension 2, it is possible to relatively easily set the first current line segment 3a and the second current line segment 3b close to each other in the manufacturing process. This may be beneficial for improving the performance and/or yield of the mems microphone.

As shown in fig. 2, the first support 7 and the support portion 8 serve to support the first current line segment 3a, the second current line segment 3b, the first magnetic resistance 4a, and the second magnetic resistance 4 b. The first support 7 and the support portion 8 may be a spacer layer between the back plate or may be part of the substrate.

The first current line section 3a comprises a first reluctance 4a and the second current line section 3b comprises a second reluctance 4 b. When the first current line segment 3a moves relative to the second current line segment, the magnetic field generated by the current in the first current line segment 3a can change the resistance of the second magnetic resistance 4b, and the magnetic field generated by the current in the second current line segment 3b can change the resistance of the first magnetic resistance 4a, so that the corresponding sound signal can be generated by changing the resistances of the first magnetic resistance and the second magnetic resistance. The first and second magnetoresistances may each generate a corresponding acoustic signal, or may be combined to generate an acoustic signal using a circuit such as a Wheatstone bridge.

As explained before, the direction of the current in the first and

second magneto resistances

4a and 4b is the same, thereby improving the sensitivity of the mems microphone. As shown in fig. 1, the direction of current flow in the first and

second magnetoresistors

4a, 4b is in the direction indicated by arrow C1. As shown in fig. 2, the current direction C1 in the first reluctance 4a and the second reluctance 4b is perpendicular to the plane of the paper. Here, in the case where the first magnetic resistance 4a and the second magnetic resistance 4b are coplanar (i.e., XY plane shown in fig. 1), the smaller one of the width of the first magnetic resistance 4a and the width of the second magnetic resistance 4b is CD 1. For example, the width of the first magnetic resistance 4a is equal to the width of the second magnetic resistance 4 b. The minimum separation between the first reluctance and the second reluctance is CD 2. The relationship between CD1 and CD2 is as follows: CD2 is less than or equal to 3 multiplied by CD 1. Alternatively, CD2 ≦ 2 × CD 1. In addition, when the CD2 is less than or equal to CD1, the sensitivity of the micro-electromechanical microphone can be obviously improved for most of magnetoresistive materials.

In addition, the current density in the magneto-resistance also has an effect on the current crowding/concentration effect described earlier. Through experiments, the inventor finds that the current density is more than or equal to 10⁶A/cm²This current crowding/concentration effect is significant in the case of (2). Therefore, the current density of the first magnetoresistance 4a is 10 or more⁶A/cm²And the current density of the second magnetoresistance 4b is 10 or more⁶A/cm². In addition, the current density is not less than 5 × 10⁶A/cm²Such current crowding/concentration effect can be ensured, thereby improving the yield of the product. Therefore, alternatively, the current density of the first magnetoresistance 4a is 5 × 10 or more⁶A/cm²And the current density of the second magnetoresistance 4b is 5 × 10 or more⁶A/cm²。

The other magnetic resistances may be provided in the same manner as the first magnetic resistance 4a and the second magnetic resistance 4 b. For example, a third current line segment 3c is also provided on the movable part 1, and a fourth current line segment 3d is also provided on the second support 2. The third current line segment 3c includes a third reluctance 4c and the fourth current line segment 3d includes a fourth reluctance 4 d. The magnetic field generated by the current of the third current line segment 3c can change the resistance of the fourth magnetic resistance 4d, and the magnetic field generated by the current of the fourth current line segment 3d can change the resistance of the third magnetic resistance 4 c.

The current in the third reluctance 4C and the fourth reluctance 4d is in the same direction as indicated by the arrow C2 in fig. 1. In the case where the third magnetoresistance 4c and the fourth magnetoresistance 4d are coplanar (i.e., XY plane shown in fig. 1), the smaller one of the width of the third magnetoresistance 4c and the width of the fourth magnetoresistance 4d is CD3, the minimum spacing between the third magnetoresistance and the fourth magnetoresistance is CD4, and the relationship of CD3 and CD4 is as follows: CD4 is less than or equal to 3 multiplied by CD 3.

As shown in fig. 3, the first magnetic resistance 4a (R1), the second magnetic resistance 4b (R2), the third magnetic resistance 4c (R3), and the fourth magnetic resistance 4d (R4) may constitute a full bridge circuit of a wheatstone bridge to output a differential sound output signal. For example, as shown in fig. 1, the

current line segments

3a, 3b, 3c, 3d and the

magnetoresistors

4a, 4b, 4c, 4d are connected to form a wheatstone bridge via

leads

5a, 5b, 5c, 5d, respectively.

Also shown in fig. 1 are

pre-bent cantilevers

6a and 6 b. Electrodes are provided on the

pre-bent cantilevers

6a and 6 b. The

pre-bent cantilevers

6a and 6b are raised with respect to the desired flat plane of the movable part 1 and the position of the movable part 1 can be adjusted by electrostatic forces. By pre-bending the

cantilevers

6a and 6b, the

magnetoresistances

4a, 4b, 4c, 4d can be accurately adjusted to default operating positions, thereby improving the detection sensitivity and accuracy.

FIG. 8 illustrates a schematic diagram of a microphone cell in accordance with one embodiment disclosed herein.

As shown in fig. 8, the microphone unit 30 includes a unit housing 31, the mems microphone 32 described above, and an integrated circuit chip 33. A mems microphone 32 and an integrated circuit chip 33 are disposed in the unitary housing 31. The mems microphone 32 corresponds to an air inlet of the single housing 31. The mems microphone 32, the integrated circuit chip 33, and the circuitry in the cell housing 31 are connected by leads 34.

FIG. 9 shows a schematic diagram of an electronic device in accordance with one embodiment disclosed herein.

As shown in fig. 9, the electronic device 40 may include the microphone unit 41 shown in fig. 8. The electronic device 40 may be a cell phone, tablet, wearable device, etc.

Although some specific embodiments of the present disclosure have been described in detail by way of example, it should be understood by those skilled in the art that the foregoing examples are for purposes of illustration only and are not intended to limit the scope of the present disclosure.

Claims

1. A microelectromechanical systems microphone, comprising:

a first support member;

a movable member provided on the first support, wherein a first current line segment is provided on the movable member; and

a second support, wherein a second current line segment is disposed on the second support,

wherein the movable member is movable in response to a change in sound pressure to move the first current line segment relative to the second current line segment,

wherein the first current line segment includes a first reluctance, the second current line segment includes a second reluctance, an

Wherein, when the first current line segment moves relative to the second current line segment, the magnetic field generated by the current in the first current line segment can change the resistance value of the second magnetic resistance, and the magnetic field generated by the current in the second current line segment can change the resistance value of the first magnetic resistance, so as to generate corresponding sound signals through the change of the resistance values of the first magnetic resistance and the second magnetic resistance,

wherein the current direction in the first magnetic resistance and the second magnetic resistance is the same,

wherein, in a case where the first magnetoresistance and the second magnetoresistance are coplanar, a smaller one of a width of the first magnetoresistance and a width of the second magnetoresistance is CD1, a minimum spacing between the first magnetoresistance and the second magnetoresistance is CD2, and a relationship of CD1 and CD2 is as follows: CD2 is less than or equal to 3 multiplied by CD 1.

2. The MEMS microphone of claim 1, wherein CD2 ≦ 2 × CD1 or CD2 ≦ CD 1.

3. The mems microphone of claim 1 or 2, wherein the first reluctance has a current density of 10 or more⁶A/cm²And the current density of the second magnetoresistance is 10 or more⁶A/cm²。

4. The mems microphone of claim 3, wherein the first reluctance has a current density of 5 x 10 or more⁶A/cm²And the current density of the second magnetoresistance is 5 × 10 or more⁶A/cm²。

5. The mems microphone of claim 1, wherein a width of the first reluctance is equal to a width of the second reluctance.

6. The mems microphone of claim 1 or 2, wherein the movable component is a first cantilever and the first current line segment is located at an end of the first cantilever, and

the second support comprises a second cantilever, the length of the second cantilever is smaller than that of the first cantilever, the second current line segment is located at the end of the second cantilever, and the end of the second cantilever is close to the end of the first cantilever.

7. A mems microphone according to claim 1 or 2, wherein a third current line segment is further provided on the movable member and a fourth current line segment is further provided on the second support;

wherein the third current line segment comprises a third magnetic resistance and the fourth current line segment comprises a fourth magnetic resistance;

the resistance value of the fourth magnetic resistance can be changed by the magnetic field generated by the current of the third current line section, and the resistance value of the third magnetic resistance can be changed by the magnetic field generated by the current of the fourth current line section;

wherein the current direction in the third magnetic resistance and the fourth magnetic resistance is the same,

wherein, in a case where the third magnetoresistance and the fourth magnetoresistance are coplanar, a smaller one of a width of the third magnetoresistance and a width of the fourth magnetoresistance is CD3, a minimum spacing between the third magnetoresistance and the fourth magnetoresistance is CD4, and a relationship of CD3 and CD4 is as follows: CD4 is less than or equal to 3 multiplied by CD 3; and

the first magnetic resistance, the second magnetic resistance, the third magnetic resistance and the fourth magnetic resistance form a full bridge circuit of a Wheatstone bridge to output differential sound output signals.

8. The mems microphone of claim 1, further comprising a pre-bent cantilever, wherein the pre-bent cantilever is raised relative to a desired flat plane of the movable part and the position of the movable part can be adjusted by electrostatic force.

9. A microphone cell comprising a cell housing, the mems microphone of claim 1, and an integrated circuit chip, wherein the mems microphone and integrated circuit chip are disposed in the cell housing.

10. An electronic device comprising the microphone cell of claim 9.