阅读说明：本技术 一种压电式麦克风及其制备工艺 (Piezoelectric microphone and preparation process thereof ) 是由 童贝 石正雨 沈宇 李杨 于 2020-07-10 设计创作，主要内容包括：本发明提供了一种压电式麦克风及其制备工艺,压电式麦克风包括具有背腔的基底和设于所述基底上的压电振膜,所述压电振膜包括固定于所述基底上的振膜层以及固定于所述振膜层上的压电单元,所述压电式麦克风还包括罩盖在所述振膜层上方的壳体,所述壳体和所述振膜层合围形成容置所述压电单元的收容腔,所述收容腔为真空环境。本发明可以增大压电单元的输出电压,提高压电式麦克风的灵敏度。(The invention provides a piezoelectric microphone and a preparation process thereof, wherein the piezoelectric microphone comprises a substrate with a back cavity and a piezoelectric diaphragm arranged on the substrate, the piezoelectric diaphragm comprises a diaphragm layer fixed on the substrate and a piezoelectric unit fixed on the diaphragm layer, the piezoelectric microphone also comprises a shell covered above the diaphragm layer, the shell and the diaphragm layer surround to form an accommodating cavity for accommodating the piezoelectric unit, and the accommodating cavity is in a vacuum environment. The invention can increase the output voltage of the piezoelectric unit and improve the sensitivity of the piezoelectric microphone.)

1. The utility model provides a piezoelectric microphone, is including the basement that has the back of the body chamber with locate piezoelectric diaphragm on the basement, piezoelectric diaphragm is including being fixed in diaphragm layer on the basement and being fixed in piezoelectric unit on the diaphragm layer, its characterized in that: the piezoelectric microphone further comprises a shell covering the upper portion of the vibration film layer, the shell and the vibration film layer are surrounded to form an accommodating cavity for accommodating the piezoelectric unit, and the accommodating cavity is in a vacuum environment.

2. The piezoelectric microphone of claim 1, wherein the housing is silicon, silicon nitride, polyethylene, or glass.

3. The piezoelectric microphone according to claim 1, wherein the base includes a side wall surrounding the back cavity, and an orthogonal projection of the piezoelectric unit in the vibration direction of the diaphragm layer partially overlaps an orthogonal projection of the side wall in the vibration direction of the diaphragm layer.

4. The piezoelectric microphone of claim 1, wherein the diaphragm layer is a unitary continuous structure.

5. The piezoelectric microphone according to claim 1, wherein the piezoelectric unit comprises a plurality of piezoelectric sheets, the plurality of piezoelectric sheets are arranged in a central symmetry manner, and adjacent two piezoelectric sheets are arranged at intervals.

6. The piezoelectric microphone according to claim 1, wherein the piezoelectric unit includes a first electrode layer, a piezoelectric layer and a second electrode layer sequentially stacked on the diaphragm layer, the first electrode layer and the second electrode layer are made of aluminum, molybdenum or titanium, and the piezoelectric layer is made of aluminum nitride, zinc oxide, scandium-doped aluminum nitride or lead zirconate titanate piezoelectric ceramic material.

7. The piezoelectric microphone according to claim 1, wherein the diaphragm layer is made of aluminum nitride, polysilicon, silicon dioxide or silicon nitride.

8. A preparation process of a piezoelectric microphone is characterized by comprising the following steps:

step S1: providing a substrate, and depositing a first oxidation layer on the surface of the substrate;

step S2: depositing a vibration film layer on the surface of the first oxidation layer;

step S3: depositing a piezoelectric unit on the surface of the vibration film layer;

step S4: etching the piezoelectric unit;

step S5: depositing on the surface of the piezoelectric unit to form a shell covering the vibration film layer, wherein the shell and the vibration film layer surround to form an accommodating cavity for accommodating the piezoelectric unit;

step S6: and etching the other surface of the substrate, which is far away from the vibration film layer, to form a back cavity.

9. The preparation process according to claim 8, wherein the step S5 specifically includes:

step S51: covering a second oxide layer on the surface of the piezoelectric unit, and performing polishing and patterning treatment;

step S52: depositing a first sealing layer on the surface of the second oxide layer;

step S53: etching the first sealing layer to form a release hole, and releasing the second oxide layer to form the accommodating cavity;

step S54: sealing the release aperture.

10. The preparation process according to claim 8, wherein the step S5 specifically includes:

step S501: depositing a peripheral wall layer on the edge of the vibrating membrane layer, wherein the peripheral wall layer surrounds the piezoelectric unit;

step S502: providing a second sealing layer;

step S503: and bonding the peripheral wall layer and the second sealing layer to form the shell.

[ technical field ] A method for producing a semiconductor device

The invention belongs to the technical field of microphones, and particularly relates to a piezoelectric microphone and a preparation process thereof.

[ background of the invention ]

An MEMS (Micro-Electro-Mechanical System) microphone is an electric transducer manufactured by using a micromachining technology, and has the characteristics of small volume, good frequency response characteristics, low noise and the like. With the development of miniaturization and lightness of electronic devices, MEMS microphones are increasingly widely used for these devices. Piezoelectric MEMS microphones have many advantages over conventional capacitive MEMS microphones, including dust and water resistance, and higher maximum output sound pressure (AOP), among others.

[ summary of the invention ]

The invention aims to provide a piezoelectric microphone and a preparation process thereof, and aims to increase the output voltage of a piezoelectric unit and improve the sensitivity of the piezoelectric microphone.

The technical scheme of the invention is as follows: the utility model provides a piezoelectric microphone, is including the basement that has the back of the body chamber with locate piezoelectric diaphragm on the basement, piezoelectric diaphragm is including being fixed in diaphragm layer on the basement and being fixed in piezoelectric unit on the diaphragm layer, its characterized in that: the piezoelectric microphone further comprises a shell covering the upper portion of the vibration film layer, the shell and the vibration film layer are surrounded to form an accommodating cavity for accommodating the piezoelectric unit, and the accommodating cavity is in a vacuum environment.

Further, the shell is made of silicon, silicon nitride, polyethylene or glass.

Further, the substrate comprises a side wall surrounding the back cavity, and the orthographic projection of the piezoelectric unit along the vibration direction of the vibration film layer is partially overlapped with the orthographic projection of the side wall along the vibration direction of the vibration film layer.

Further, the diaphragm layer is of an integral continuous structure.

Further, the piezoelectric unit comprises a plurality of piezoelectric sheets, the plurality of piezoelectric sheets are arranged in a central symmetry manner, and two adjacent piezoelectric sheets are arranged at intervals.

Further, the piezoelectric unit comprises a first electrode layer, a piezoelectric layer and a second electrode layer which are sequentially stacked on the vibration film layer, the first electrode layer and the second electrode layer are made of aluminum, molybdenum or titanium, and the piezoelectric layer is made of aluminum nitride, zinc oxide, scandium-doped aluminum nitride or lead zirconate titanate piezoelectric ceramic.

Further, the vibration film layer is made of aluminum nitride, polysilicon, silicon dioxide or silicon nitride.

The invention also provides a preparation process of the piezoelectric microphone, which comprises the following steps:

step S1: providing a substrate, and depositing a first oxidation layer on the surface of the substrate;

step S2: depositing a vibration film layer on the surface of the first oxidation layer;

step S3: depositing a piezoelectric unit on the surface of the vibration film layer;

step S4: etching the piezoelectric unit;

step S5: depositing on the surface of the piezoelectric unit to form a shell covering the vibration film layer, wherein the shell and the vibration film layer surround to form an accommodating cavity for accommodating the piezoelectric unit;

step S6: and etching the other surface of the substrate, which is far away from the vibration film layer, to form a back cavity.

Further, step S5 specifically includes:

step S51: covering a second oxide layer on the surface of the piezoelectric unit, and performing polishing and patterning treatment;

step S52: depositing a first sealing layer on the surface of the second oxide layer;

step S53: etching the first sealing layer to form a release hole, and releasing the second oxide layer to form the accommodating cavity;

step S54: sealing the release aperture.

Further, the step S5 specifically includes:

step S501: depositing a peripheral wall layer on the edge of the vibrating membrane layer, wherein the peripheral wall layer surrounds the piezoelectric unit;

step S502: providing a second sealing layer;

step S503: and bonding the peripheral wall layer and the second sealing layer to form the shell.

The invention has the beneficial effects that: through setting up the casing in the top of shake rete, casing and shake rete surround the chamber of acceping that forms holding piezoelectric unit, and accept the chamber and be vacuum environment, consequently shake the air damping that the rete received when the vibration significantly reduces, the output voltage of piezoelectric unit can increase under the same acoustic pressure effect, has effectively improved the sensitivity of microphone.

[ description of the drawings ]

Fig. 1 is a schematic overall structure diagram of a piezoelectric microphone according to a first embodiment of the present invention;

fig. 2 is an exploded schematic view of a piezoelectric microphone according to a first embodiment of the present invention;

FIG. 3 is a schematic sectional view taken along line A-A of FIG. 1;

fig. 4 is a flow chart illustrating a process for manufacturing a piezoelectric microphone according to a second embodiment of the present invention;

fig. 5 to 13 are schematic views illustrating a manufacturing process of a piezoelectric microphone according to a second embodiment of the present invention;

FIG. 14 is a schematic view of a third embodiment of the present invention illustrating a process for depositing a peripheral wall layer on the edge of the diaphragm layer;

fig. 15 is a schematic view of a manufacturing process of providing a second sealing layer on the peripheral wall layer according to the third embodiment of the present invention.

[ detailed description ] embodiments

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