阅读说明：本技术 压电式mems麦克风 (Piezoelectric MEMS microphone ) 是由 段炼 张睿 陈志远 于 2019-08-16 设计创作，主要内容包括：本发明提供一种压电式MEMS麦克风,包括具有腔体的基底和设置在基底上的压电振膜,基底包括环形底座以及设于环形底座内侧并与环形底座间隔设置的支撑柱,压电振膜包括多个沿支撑柱周向间隔设置的膜片,每一膜片包括与支撑柱连接的固定端和悬置于腔体上方的自由端,膜片的宽度由固定端朝向自由端逐渐增大。本发明的压电式MEMS麦克风,在声压的作用下,自由端发生振动,由宽的自由端带动短的固定端,靠近固定端的膜片发生更大的形变进而产生较多的电荷,因此,灵敏度可以进一步提高。(The invention provides a piezoelectric type MEMS microphone, which comprises a substrate with a cavity and a piezoelectric diaphragm arranged on the substrate, wherein the substrate comprises an annular base and supporting columns arranged on the inner side of the annular base and spaced from the annular base, the piezoelectric diaphragm comprises a plurality of diaphragms arranged at intervals along the circumferential direction of the supporting columns, each diaphragm comprises a fixed end connected with the supporting columns and a free end suspended above the cavity, and the width of each diaphragm is gradually increased from the fixed end to the free end. According to the piezoelectric MEMS microphone, under the action of sound pressure, the free end vibrates, the wide free end drives the short fixed end, and the diaphragm close to the fixed end deforms more greatly to generate more charges, so that the sensitivity can be further improved.)

1. The utility model provides a piezoelectric type MEMS microphone, its characterized in that is in including the basement that has the cavity and setting piezoelectricity vibrating diaphragm on the basement, the basement includes annular base and locates annular base inboard and with the support column that the annular base interval set up, piezoelectricity vibrating diaphragm includes a plurality of edges the diaphragm that support column circumference interval set up, each the diaphragm include with stiff end and suspension that the support column is connected in the free end of cavity top, the width of diaphragm by the stiff end orientation the free end crescent.

2. the piezoelectric MEMS microphone according to claim 1, wherein the substrate further comprises a plurality of supporting beams spaced apart from each other, one end of the supporting beam is connected to the supporting column, the other end of the supporting beam is connected to the ring-shaped base, so as to divide the cavity into a plurality of sub-cavities spaced apart from each other along the circumferential direction of the supporting column, and the free end is suspended above the sub-cavities.

3. The piezoelectric MEMS microphone of claim 2, wherein one of the free ends is suspended above each of the sub-cavities.

4. The piezoelectric MEMS microphone of claim 3, wherein a projected contour of the free end in the direction of vibration is located within a projected contour of the sub-cavity in the direction of vibration.

5. The piezoelectric MEMS microphone according to claim 4, wherein a projection profile of the free end in a vibration direction is the same shape as a projection profile of the corresponding sub-cavity in the vibration direction.

6. the piezoelectric MEMS microphone according to claim 5, wherein a first wall is disposed on a side of the annular base facing the supporting pillar, a second wall is disposed on a side of the supporting pillar facing the annular base, and a projection profile of the first wall and the second wall in a vibration direction are both circular.

7. The piezoelectric MEMS microphone of claim 6, wherein a projected profile of the diaphragm in a vibration direction is fan-shaped.

8. the piezoelectric MEMS microphone according to claim 6, wherein the projected outlines of the first wall and the second wall in the vibration direction are both polygonal.

9. The piezoelectric MEMS microphone of claim 8, wherein a projected profile of the diaphragm in a vibration direction is trapezoidal.

10. The piezoelectric MEMS microphone according to claim 6, wherein one of a projected contour of the first wall in a vibration direction and a projected contour of the second wall in a vibration direction is a circle and the other is a polygon.

[ technical field ] A method for producing a semiconductor device

The invention relates to the technical field of acoustoelectric conversion devices, in particular to a piezoelectric type MEMS microphone.

[ background of the invention ]

The MEMS microphone is an electroacoustic transducer manufactured by a micromachining technology and has the characteristics of small volume, good frequency response characteristic, low noise and the like. As electronic devices are miniaturized and thinned, MEMS microphones are widely used for these devices.

At present, MEMS microphones are mainly classified into capacitive MEMS microphones and piezoelectric MEMS microphones. Piezoelectric MEMS microphones have many advantages over conventional capacitive MEMS microphones, including dust resistance, water resistance, and higher maximum output sound pressure (AOP). The piezoelectric diaphragm structure is different from that of a capacitor microphone, the piezoelectric diaphragm of the piezoelectric MEMS microphone is composed of a plurality of diaphragms, one end of each diaphragm is connected with a substrate, and the other end of each diaphragm is of a cantilever beam structure to avoid deformation of residual stress in the process on the surface of the diaphragm so as to reduce noise and improve sensitivity.

Fig. 1 to 4 show two typical piezoelectric MEMS microphone designs, which are characterized in that the fixed end 211 of the diaphragm 21 on the piezoelectric diaphragm 20 is located on the periphery of the cavity 14 on the substrate 10, the free end 212 is located at the center, and the shape of the diaphragm 21 is a triangular or fan-shaped structure with gradually decreasing cantilever beam width from the fixed end 211 to the free end 212. Under the effect of acoustic pressure, free end 212 drives the cantilever beam and takes place the vibration, and the diaphragm 21 that is close to stiff end 211 produces the voltage under the effect of power, and the sound pressure arouses the cantilever beam deformation when outside sound signal spreads into from the phonate hole, produces voltage variation to perception acoustic signal. In practical applications, for a given membrane 21 material and MEMS Die size, the sensitivity of the design shown in fig. 1-4 is limited, and regardless of the ASIC gain, the sensitivity of MEMS Die is typically around-43 dB, which is difficult to be increased to-40 dB or more.

Therefore, in order to further improve the sensitivity of the piezoelectric MEMS microphone, it is necessary to provide a new piezoelectric MEMS microphone, which improves the overall structure and improves the sensitivity to solve the above problems.

[ summary of the invention ]

The invention aims to provide a piezoelectric MEMS microphone with high sensitivity.

The technical scheme of the invention is as follows:

In order to achieve the above object, the present invention provides a piezoelectric MEMS microphone, including a substrate having a cavity and a piezoelectric diaphragm disposed on the substrate, where the substrate includes an annular base and supporting pillars disposed inside the annular base and spaced from the annular base, the piezoelectric diaphragm includes a plurality of diaphragms disposed at intervals along a circumferential direction of the supporting pillars, each diaphragm includes a fixed end connected to the supporting pillars and a free end suspended above the cavity, and a width of the diaphragm gradually increases from the fixed end toward the free end.

As an improvement mode, the basement still includes a plurality of interval setting's a supporting beam, thereby the one end of supporting beam with the support column is connected, the other end with the annular base is connected thereby will the cavity is separated into a plurality of and is followed the sub-cavity of the circumference interval setting of support column, the free end suspension in sub-cavity top.

As a refinement, one of the free ends is suspended above each of the sub-cavities.

As a refinement, the projection profile of the free end in the direction of vibration is located within the projection profile of the sub-cavity in the direction of vibration.

As a modification, the projection profile of the free end in the vibration direction is the same as the projection profile of the corresponding sub-cavity in the vibration direction.

As an improvement, a first wall body is arranged on one side of the annular base facing the supporting column, a second wall body is arranged on one side of the supporting column facing the annular base, and projection outlines of the first wall body and the second wall body in the vibration direction are both circular.

As a refinement, the projection contour of the diaphragm in the direction of vibration has a fan shape.

As a refinement, the projection outlines of the first wall body and the second wall body in the vibration direction are both polygonal.

As a refinement, the projection profile of the diaphragm in the direction of vibration is trapezoidal.

As an improvement, one of a projection profile of the first wall body in the vibration direction and a projection profile of the second wall body in the vibration direction is a circle, and the other is a polygon.

the invention has the beneficial effects that:

According to the piezoelectric MEMS microphone, under the action of sound pressure, the free end vibrates, and the piezoelectric diaphragm close to the fixed end generates a voltage signal. Compare in traditional design, the width of diaphragm is by stiff end towards the free end crescent, and this design drives short stiff end by wide free end, and the diaphragm that is close to the stiff end takes place bigger deformation and then produces more electric charge, consequently, sensitivity can further improve.

[ description of the drawings ]

FIG. 1 is a top view of a first prior art piezoelectric MEMS microphone;

FIG. 2 is a cross-sectional view taken at A-A of FIG. 1;

FIG. 3 is a top view of a second piezoelectric MEMS microphone of the prior art;

FIG. 4 is a cross-sectional view taken at B-B of FIG. 3;

FIG. 5 is a perspective view of a piezoelectric MEMS microphone according to an embodiment of the present invention;

FIG. 6 is an exploded view of a piezoelectric MEMS microphone according to an embodiment of the present invention;

FIG. 7 is a top view of a piezoelectric MEMS microphone according to an embodiment of the present invention;

FIG. 8 is a cross-sectional view taken at C-C of FIG. 7;

FIG. 9 is a first perspective view of a substrate provided in accordance with an embodiment of the present invention;

FIG. 10 is a second perspective view of a substrate provided in accordance with an embodiment of the present invention;

FIG. 11 is a third perspective view of a substrate provided in accordance with an embodiment of the present invention;

fig. 12 is a fourth perspective view of a substrate according to an embodiment of the invention.

[ detailed description ] embodiments

the invention is further described with reference to the following figures and embodiments.

It should be noted that all the directional indicators (such as upper, lower, inner, outer, top, bottom … …) in the embodiment of the present invention are only used to explain the relative position relationship between the components in a specific posture (as shown in the drawings), and if the specific posture is changed, the directional indicator is changed accordingly.

It will also be understood that when an element is referred to as being "secured to" or "disposed on" another element, it can be directly on the other element or intervening elements may also be present. When an element is referred to as being "connected" to another element, it can be directly connected to the other element or intervening elements may also be present.

Referring to fig. 5 to 12, an embodiment of the present invention provides a piezoelectric MEMS microphone, which includes a substrate 30 and a piezoelectric diaphragm 40 disposed on the substrate 30, wherein an external sound signal is transmitted from a sound hole, and a sound pressure generated by the sound causes the piezoelectric diaphragm 40 to deform, generate a voltage change, and thus sense an acoustic signal.

Referring to fig. 5 to 8, the base 30 includes an annular base 31, support pillars 32 disposed on an inner side of the annular base 31 and spaced from the annular base 31, and a plurality of support beams 33 disposed at intervals along a circumferential direction of the support pillars 32, the base 30 has a cavity 34, the support pillars 32 are connected to the annular base 31 through the support beams 33, the annular base 31 and the support pillars 32 enclose the annular cavity 34, one end of the support beams 33 is connected to the support pillars 32, and the other end of the support beams 33 is connected to the annular base 31 so as to divide the cavity 34 into a plurality of sub-cavities 35 disposed at intervals along the circumferential direction of the support pillars 32, and the annular base 31 may be in a 360-degree closed ring shape or not in a complete ring shape.

The piezoelectric diaphragm 40 includes a plurality of diaphragms 41 arranged at intervals along the circumferential direction of the supporting column 32, each diaphragm 41 includes a fixed end 411 connected to the supporting column 32 and a free end 412 connected to the fixed end 411 and suspended above the sub-cavity 35, and the diaphragms 41 are arranged in a cantilever beam. The diaphragm 41 extends from the fixed end 411 to the free end 412 in a form that the width size gradually increases, so that under the action of sound pressure, the free end 412 drives the diaphragm 41 with a cantilever structure to vibrate, and the part of the diaphragm 41 close to the fixed end 411 deforms more under the action of force to generate more charges, so that the sensitivity of the diaphragm can be further improved. In a specific experiment, under the condition that the MEMS chip and the film layer structure with the same area are not changed, the structural design can improve the sensitivity value to be more than-37 dB, and the sensitivity of-43 dB is obviously improved compared with that of a traditional structure.

In this embodiment, a free end 412 is suspended above each sub-cavity 35, a first wall 311 is disposed on one side (inner side wall of the annular base 31) of the annular base 31 facing the supporting column 32, a projection profile of the first wall 311 in the vibration direction may be circular or polygonal, the number of the supporting beams 33 may be set according to actual needs, the specific number is not limited, and when the projection profile of the first wall 311 in the vibration direction is polygonal, the number of the supporting beams 33 may be smaller than, equal to, or larger than the number of vertices of the polygon. It should be noted that two or more free ends 412 may be suspended above each subcavity 35, depending on the actual design requirements.

in a preferred embodiment, the projection profile of the free end 412 in the vibration direction is located within the projection profile of the sub-cavities 35 in the vibration direction, and there is a corresponding free end 412 in each sub-cavity 35. Preferably, the projection profile of the free end 412 in the vibration direction is the same as the projection profile of the corresponding sub-cavity 35 in the vibration direction, so that the piezoelectric diaphragm 40 can cover the cavity 34, and the influence of the excessive interval between the piezoelectric diaphragm 40 and the substrate 30 on the sound production effect is avoided.

Referring to fig. 9, specifically, the second wall 321 is disposed on a side of the supporting pillar 32 facing the annular base 31, and the projection profiles of the first wall 311 and the second wall 321 in the vibration direction are both polygonal, at this time, the projection profile of the diaphragm 41 in the vibration direction is trapezoidal, and the outer profile of the whole piezoelectric diaphragm 40 is polygonal.

Of course, the shape of the substrate 30 is not limited to the above, and referring to fig. 10, the projected outlines of the first wall 311 and the second wall 321 in the vibration direction may also be both circular, and the projected outline of the single diaphragm 41 in the vibration direction is fan-shaped.

Alternatively, referring to fig. 11 to 12, one of the projected contour of the first wall 311 in the vibration direction and the projected contour of the second wall 321 in the vibration direction is a circle, and the other is a polygon.

In this embodiment, the specific structures of the fixed end 411 and the diaphragm 41 are not limited, and the symmetry of the whole structure of the piezoelectric diaphragm 40 is also not limited, the diaphragm 41 may be a symmetrical or asymmetrical polygon, the side edge of the diaphragm 41 may be a straight line or a curved line, and the width of the free end 412 of the diaphragm 41 is greater than the width of the fixed end 411 of the diaphragm 41.

while the foregoing is directed to embodiments of the present invention, it will be understood by those skilled in the art that various changes may be made without departing from the spirit and scope of the invention.