CN111669690A - Piezoelectric microphone and preparation process thereof - Google Patents
Piezoelectric microphone and preparation process thereof Download PDFInfo
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- CN111669690A CN111669690A CN202010662477.1A CN202010662477A CN111669690A CN 111669690 A CN111669690 A CN 111669690A CN 202010662477 A CN202010662477 A CN 202010662477A CN 111669690 A CN111669690 A CN 111669690A
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- 238000002360 preparation method Methods 0.000 title claims abstract description 9
- 239000000758 substrate Substances 0.000 claims abstract description 28
- 238000000151 deposition Methods 0.000 claims description 23
- 230000002093 peripheral effect Effects 0.000 claims description 19
- 238000007789 sealing Methods 0.000 claims description 19
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims description 12
- PMHQVHHXPFUNSP-UHFFFAOYSA-M copper(1+);methylsulfanylmethane;bromide Chemical compound Br[Cu].CSC PMHQVHHXPFUNSP-UHFFFAOYSA-M 0.000 claims description 12
- 238000005530 etching Methods 0.000 claims description 12
- 229910052581 Si3N4 Inorganic materials 0.000 claims description 9
- HQVNEWCFYHHQES-UHFFFAOYSA-N silicon nitride Chemical compound N12[Si]34N5[Si]62N3[Si]51N64 HQVNEWCFYHHQES-UHFFFAOYSA-N 0.000 claims description 9
- XLOMVQKBTHCTTD-UHFFFAOYSA-N Zinc monoxide Chemical compound [Zn]=O XLOMVQKBTHCTTD-UHFFFAOYSA-N 0.000 claims description 8
- 235000012239 silicon dioxide Nutrition 0.000 claims description 6
- 239000000377 silicon dioxide Substances 0.000 claims description 6
- ZOKXTWBITQBERF-UHFFFAOYSA-N Molybdenum Chemical compound [Mo] ZOKXTWBITQBERF-UHFFFAOYSA-N 0.000 claims description 5
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 claims description 5
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 claims description 5
- 229910052782 aluminium Inorganic materials 0.000 claims description 5
- 229910052750 molybdenum Inorganic materials 0.000 claims description 5
- 239000011733 molybdenum Substances 0.000 claims description 5
- 230000003647 oxidation Effects 0.000 claims description 5
- 238000007254 oxidation reaction Methods 0.000 claims description 5
- 229910052710 silicon Inorganic materials 0.000 claims description 5
- 239000010703 silicon Substances 0.000 claims description 5
- 229910052719 titanium Inorganic materials 0.000 claims description 5
- 239000010936 titanium Substances 0.000 claims description 5
- 239000004698 Polyethylene Substances 0.000 claims description 4
- 239000011521 glass Substances 0.000 claims description 4
- HFGPZNIAWCZYJU-UHFFFAOYSA-N lead zirconate titanate Chemical compound [O-2].[O-2].[O-2].[O-2].[O-2].[Ti+4].[Zr+4].[Pb+2] HFGPZNIAWCZYJU-UHFFFAOYSA-N 0.000 claims description 4
- 229910052451 lead zirconate titanate Inorganic materials 0.000 claims description 4
- 229910021420 polycrystalline silicon Inorganic materials 0.000 claims description 4
- -1 polyethylene Polymers 0.000 claims description 4
- 229920000573 polyethylene Polymers 0.000 claims description 4
- 229920005591 polysilicon Polymers 0.000 claims description 4
- 239000011787 zinc oxide Substances 0.000 claims description 4
- 238000000059 patterning Methods 0.000 claims description 3
- 238000005498 polishing Methods 0.000 claims description 3
- 229910010293 ceramic material Inorganic materials 0.000 claims description 2
- 239000012528 membrane Substances 0.000 claims description 2
- 230000035945 sensitivity Effects 0.000 abstract description 7
- 238000000034 method Methods 0.000 description 11
- 239000000463 material Substances 0.000 description 9
- 238000004519 manufacturing process Methods 0.000 description 6
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 4
- 238000013016 damping Methods 0.000 description 3
- 239000000919 ceramic Substances 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 238000005516 engineering process Methods 0.000 description 2
- 229920000642 polymer Polymers 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 1
- 210000000746 body region Anatomy 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 238000001312 dry etching Methods 0.000 description 1
- 239000000428 dust Substances 0.000 description 1
- 230000005496 eutectics Effects 0.000 description 1
- 238000004518 low pressure chemical vapour deposition Methods 0.000 description 1
- 238000005459 micromachining Methods 0.000 description 1
- 238000000623 plasma-assisted chemical vapour deposition Methods 0.000 description 1
- 239000000565 sealant Substances 0.000 description 1
- 239000004065 semiconductor Substances 0.000 description 1
- 229910000679 solder Inorganic materials 0.000 description 1
- 239000011800 void material Substances 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
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Classifications
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
- H04R17/00—Piezoelectric transducers; Electrostrictive transducers
- H04R17/02—Microphones
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
- H04R1/00—Details of transducers, loudspeakers or microphones
- H04R1/20—Arrangements for obtaining desired frequency or directional characteristics
- H04R1/22—Arrangements for obtaining desired frequency or directional characteristics for obtaining desired frequency characteristic only
- H04R1/28—Transducer mountings or enclosures modified by provision of mechanical or acoustic impedances, e.g. resonator, damping means
- H04R1/2807—Enclosures comprising vibrating or resonating arrangements
- H04R1/283—Enclosures comprising vibrating or resonating arrangements using a passive diaphragm
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
- H04R31/00—Apparatus or processes specially adapted for the manufacture of transducers or diaphragms therefor
- H04R31/003—Apparatus or processes specially adapted for the manufacture of transducers or diaphragms therefor for diaphragms or their outer suspension
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
- H04R2231/00—Details of apparatus or processes specially adapted for the manufacture of transducers or diaphragms therefor covered by H04R31/00, not provided for in its subgroups
- H04R2231/003—Manufacturing aspects of the outer suspension of loudspeaker or microphone diaphragms or of their connecting aspects to said diaphragms
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- Engineering & Computer Science (AREA)
- Physics & Mathematics (AREA)
- Acoustics & Sound (AREA)
- Signal Processing (AREA)
- Manufacturing & Machinery (AREA)
- Health & Medical Sciences (AREA)
- Otolaryngology (AREA)
- Piezo-Electric Transducers For Audible Bands (AREA)
Abstract
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.
Description
[ 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.
In the related art, the piezoelectric MEMS microphone diaphragm is composed of a plurality of diaphragms, and the plurality of diaphragms are fixed on a substrate having a back cavity by elastic connection, and the upper and lower portions of the diaphragm are air. After the piezoelectric type MEMS microphone is packaged, the motion of the diaphragm is blocked by the closed air environment, so that the output voltage of the piezoelectric unit is reduced, and the sensitivity of the MEMS microphone is greatly reduced.
[ 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.
Example (b):
referring to fig. 1 to 2, a piezoelectric microphone according to a first embodiment of the present invention includes a substrate 1 having a back cavity 4, and a piezoelectric diaphragm 2 disposed on the substrate 1, where the piezoelectric diaphragm 2 includes a diaphragm layer 21 fixed on the substrate 1 and a piezoelectric unit 22 fixed on the diaphragm layer 21. The piezoelectric unit 22 is pressed to drive the diaphragm layer 21 to deform in the space above the back cavity 4, so as to generate a voltage signal.
In this embodiment, as shown in fig. 2, the piezoelectric microphone further includes a casing 3 covering the diaphragm layer 21, the casing 3 and the diaphragm layer 21 surround to form an accommodating cavity 5 for accommodating the piezoelectric unit 22, and the accommodating cavity 5 is a vacuum environment. Through setting up the casing 3 of shroud in the diaphragm layer 21 top, casing 3 and diaphragm layer 21 surround and form the chamber 5 of acceping of holding piezoelectric unit 22, and it is the vacuum environment to accept chamber 5, therefore the air damping that diaphragm layer 21 received when the vibration significantly reduces, compares in the correlation technique, and the output voltage of piezoelectric unit 22 can increase under the same acoustic pressure effect, has effectively improved the sensitivity of microphone.
Specifically, the housing 3 includes a peripheral wall 31 disposed along the peripheral direction of the diaphragm layer 21 and a top wall 32 covering the peripheral wall 31 on the side away from the diaphragm layer 21, where the peripheral wall 31 is fixed to the diaphragm layer 21 and the peripheral wall 31 is flush with the edge of the diaphragm layer 21. The peripheral wall 31 is flush with the edge of the diaphragm layer 21, so that the piezoelectric microphone is balanced and stable as a whole and is more attractive. The diaphragm layer 21 of the present embodiment has an integral continuous structure, and no fault or void exists in the diaphragm layer 21, so that the vacuum chamber 5 can be formed in a complete vacuum above the diaphragm layer 21.
Preferably, the housing 3 is made of silicon, silicon nitride, polyethylene or glass, but the housing 3 may be made of a combination of silicon nitride, polyethylene or glass.
Further, the substrate 1 includes a side wall 11 surrounding the back cavity 4, and an orthogonal projection of the piezoelectric unit 22 along the vibration direction of the diaphragm layer 21 partially overlaps an orthogonal projection of the side wall 11 along the vibration direction of the diaphragm layer 21. That is, the edge of the piezoelectric element 22 at least partially extends laterally beyond the edge of the back cavity 4, so that when the diaphragm layer 21 vibrates, the portion of the piezoelectric element 22 corresponding to the edge of the back cavity 4 is subjected to a larger stress, thereby further increasing the output voltage of the piezoelectric element 22.
The piezoelectric unit 22 of the present embodiment includes a first electrode layer 222, a piezoelectric layer 223, and a second electrode layer 224 sequentially stacked on the diaphragm layer 21, and edges of the first electrode layer 222, the piezoelectric layer 223, and the second electrode layer 224 are flush with each other. The substrate 1 is a micro silicon substrate, the vibration film layer 21 is disposed on the substrate 1, the first electrode layer 222 is disposed on the vibration film layer 21, the piezoelectric layer 223 is disposed on the first electrode layer 222, and the second electrode layer 224 is disposed on the piezoelectric layer 223. The first electrode layer 222 and the second electrode layer 224 are made of aluminum, molybdenum or titanium, or a combination of the above materials, the piezoelectric layer 223 is made of aluminum nitride, scandium-doped aluminum nitride, zinc oxide or lead zirconate titanate piezoelectric ceramic, or a combination of the above materials, and the vibration film layer 21 is made of aluminum nitride, polysilicon, silicon dioxide or silicon nitride, or a combination of the above materials. In this embodiment, the number of layers of the piezoelectric unit 22 is three, and in other embodiments, the number of layers of the piezoelectric unit 22 may also be four, five, six, or more, which is not limited in this embodiment.
The piezoelectric unit 22 includes a plurality of piezoelectric sheets 221, the plurality of piezoelectric sheets 221 are arranged in a central symmetry manner, and two adjacent piezoelectric sheets 221 are arranged at intervals. Preferably, the piezoelectric unit 22 includes four piezoelectric patches 221, the four piezoelectric patches 221 are all in a triangular structure, the four piezoelectric patches 221 have the same size, and the four piezoelectric patches 221 surround to form a square structure. The piezoelectric unit 22 is composed of a plurality of piezoelectric sheets 221 arranged at intervals, each piezoelectric sheet 221 extends from above the central position of the diaphragm layer 21 to above the edge of the diaphragm layer 21, so that the central area of a piezoelectric area has a larger deformation amount, the sensitivity of the piezoelectric microphone is improved, the uniformity of product performance is improved, and the piezoelectric sheets 221 can be arranged at equal intervals to improve the consistency and uniformity of product structures. In other possible embodiments, the piezoelectric sheet 221 may also have a fan-shaped structure, and a plurality of fan-shaped piezoelectric sheets 221 surround to form a circular structure.
Referring to fig. 4, a second embodiment of the present invention further provides a process for manufacturing a piezoelectric microphone, including the following steps:
step S1: providing a substrate 1, and depositing a first oxide layer 6 on the surface of the substrate 1, as shown in fig. 5;
specifically, the substrate 1 is a micro silicon substrate, and before the first oxide layer 6 is deposited, the substrate 1 may be cleaned. The first oxide layer 6 may be silicon dioxide and may be formed by a low pressure chemical vapor deposition process or a plasma enhanced chemical vapor deposition process.
Step S2: depositing a vibration film layer 21 on the surface of the first oxide layer 6, as shown in fig. 6;
specifically, the diaphragm layer 21 is made of aluminum nitride, polysilicon, silicon dioxide, polymer or silicon nitride, or a combination of these materials.
Step S3: depositing a piezoelectric unit 22 on the surface of the diaphragm layer 21, as shown in fig. 7;
specifically, the method comprises the following substeps:
step S31: and depositing a first electrode layer 222 on the surface of the diaphragm layer 21, wherein the first electrode layer 222 is made of aluminum, molybdenum or titanium material, or a combination of the materials.
Step S32: a piezoelectric layer 223 is deposited on the surface of the first electrode layer 222, and the piezoelectric layer 223 is made of aluminum nitride, scandium-doped aluminum nitride, zinc oxide, or lead zirconate titanate piezoelectric ceramic material, or a combination of the above materials.
Step S33: a second electrode layer 224 is deposited on the surface of the piezoelectric layer 223, and the second electrode layer 224 is made of aluminum, molybdenum or titanium, or a combination of the above materials.
Step S4: etching the piezoelectric unit 22, as shown in fig. 8;
specifically, a plurality of piezoelectric patches 221 are formed by dry etching, the plurality of piezoelectric patches 221 are arranged in a central symmetry manner, and two adjacent piezoelectric patches 221 are arranged at intervals.
Step S5: depositing on the surface of the piezoelectric unit 22 to form a shell 3 covering the vibration film layer 21, and enclosing the shell 3 and the vibration film layer 21 to form an accommodating cavity 5 for accommodating the piezoelectric unit 22;
it should be noted that, the step S5 is prepared in a vacuum environment, so as to ensure that the finally formed receiving cavity 5 is in a vacuum environment. Specifically, step S5 includes the following sub-steps:
step S51: the surface of the piezoelectric unit 22 is covered with the second oxide layer 7, and polishing and patterning processes are performed, as shown in fig. 9. Specifically, the second oxide layer 7 is silicon dioxide.
Step S52: depositing a first sealing layer 8 on the surface of the second oxide layer 7, as shown in fig. 10; the first sealing layer 8 is made of silicon nitride or polymer.
Step S53: etching the first sealing layer 8 to form a release hole 81, and releasing the second oxide layer 7 to form a receiving cavity 5, as shown in fig. 11;
the release hole 81 is used for removing the second oxide layer 7 between the first sealing layer 8 and the diaphragm layer 21 in the central main body region until the diaphragm layer 21 is exposed, and a containing cavity 5 for containing the piezoelectric unit 22 is formed.
Step S54: the release hole 81 is sealed as shown in fig. 12. The same material as the first sealing layer 8 may be deposited in the area of the release hole 81 to seal the release hole 81.
Step S6: the other surface of the substrate 1 facing away from the diaphragm layer 21 is etched to form the back cavity 4, as shown in figure 13. Specifically, ICP deep etching is performed on the other surface of the substrate 1 away from the diaphragm layer 21, the etching is stopped at the first oxide layer 6, an area of the back cavity 4 is formed, then a BOE solution or HF gas phase etching technology is adopted to release the first oxide layer 6, and finally the piezoelectric microphone according to the embodiment of the invention is formed.
The third embodiment of the present invention provides a process for manufacturing a piezoelectric microphone, and the only difference between the third embodiment and the second embodiment is that the method for depositing the case 3 on the surface of the piezoelectric unit 22 is different. Specifically, the method comprises the following steps:
step S11: providing a substrate 1, and depositing a first oxidation layer 6 on the surface of the substrate 1;
step S21: depositing a vibration film layer 21 on the surface of the first oxide layer 6;
step S31: depositing a piezoelectric unit 22 on the surface of the vibration film layer 21;
step S41: etching the piezoelectric unit 22;
step S51: a shell 3 covering the upper part of the vibration film layer 21 is formed on the surface of the piezoelectric unit 22, and the shell 3 and the vibration film layer 21 surround to form an accommodating cavity 5 for accommodating the piezoelectric unit 22;
step S51 includes the following substeps:
step S501: a peripheral wall layer 70 is deposited on the edge of the diaphragm layer 21, and the peripheral wall layer 70 surrounds the piezoelectric unit 22, as shown in fig. 14.
Step S502: a second sealant layer 80 is provided as shown in fig. 15.
Step S503: the peripheral wall layer 70 and the second sealing layer 80 are bonded, so that the top of the peripheral wall layer 70 and the second sealing layer 80 are sealed to form the accommodating cavity 5 for accommodating the piezoelectric unit 22. Specifically, the peripheral wall layer 70 and the second sealing layer 80 may be bonded by eutectic bonding, anodic bonding, or low-temperature solder bonding.
Step S61: the other surface of the substrate 1 facing away from the diaphragm layer 21 is etched to form the back cavity 4.
In summary, in the piezoelectric microphone according to the embodiment of the present invention, the casing 3 is disposed above the diaphragm layer 21, and the casing 3 and the diaphragm layer 21 surround to form the vacuum chamber 5 for accommodating the piezoelectric unit 22, so that air damping received by the diaphragm layer 21 during vibration is greatly reduced, output voltage of the piezoelectric unit 22 is increased under the same sound pressure, and sensitivity of the microphone is effectively improved.
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.
Claims (10)
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.
Priority Applications (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202010662477.1A CN111669690A (en) | 2020-07-10 | 2020-07-10 | Piezoelectric microphone and preparation process thereof |
| PCT/CN2020/104047 WO2022007016A1 (en) | 2020-07-10 | 2020-07-24 | Piezoelectric microphone and preparation process therefor |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202010662477.1A CN111669690A (en) | 2020-07-10 | 2020-07-10 | Piezoelectric microphone and preparation process thereof |
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| CN111669690A true CN111669690A (en) | 2020-09-15 |
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| CN202010662477.1A Pending CN111669690A (en) | 2020-07-10 | 2020-07-10 | Piezoelectric microphone and preparation process thereof |
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| CN (1) | CN111669690A (en) |
| WO (1) | WO2022007016A1 (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2022116288A1 (en) * | 2020-12-01 | 2022-06-09 | 瑞声声学科技(深圳)有限公司 | Piezoelectric microphone |
| TWI852052B (en) | 2021-08-11 | 2024-08-11 | 大陸商深圳市韶音科技有限公司 | Sound transmitter |
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