CN1119917C - Cantilever-type vibration membrane structure for miniature microphone and loudspeaker and its making method - Google Patents
Cantilever-type vibration membrane structure for miniature microphone and loudspeaker and its making method Download PDFInfo
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- CN1119917C CN1119917C CN 00105555 CN00105555A CN1119917C CN 1119917 C CN1119917 C CN 1119917C CN 00105555 CN00105555 CN 00105555 CN 00105555 A CN00105555 A CN 00105555A CN 1119917 C CN1119917 C CN 1119917C
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- 238000000034 method Methods 0.000 title claims description 7
- 239000012528 membrane Substances 0.000 title description 3
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims abstract description 40
- 229910052581 Si3N4 Inorganic materials 0.000 claims abstract description 24
- 239000002184 metal Substances 0.000 claims abstract description 24
- 229910052751 metal Inorganic materials 0.000 claims abstract description 24
- HQVNEWCFYHHQES-UHFFFAOYSA-N silicon nitride Chemical compound N12[Si]34N5[Si]62N3[Si]51N64 HQVNEWCFYHHQES-UHFFFAOYSA-N 0.000 claims abstract description 24
- 239000000377 silicon dioxide Substances 0.000 claims abstract description 20
- 239000000758 substrate Substances 0.000 claims abstract description 20
- 235000012239 silicon dioxide Nutrition 0.000 claims abstract description 19
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 claims abstract description 15
- 229910052710 silicon Inorganic materials 0.000 claims abstract description 15
- 239000010703 silicon Substances 0.000 claims abstract description 15
- 238000002360 preparation method Methods 0.000 claims abstract description 9
- 238000003980 solgel method Methods 0.000 claims abstract description 5
- 239000010409 thin film Substances 0.000 claims description 27
- 238000000151 deposition Methods 0.000 claims description 16
- 230000008021 deposition Effects 0.000 claims description 16
- 239000003292 glue Substances 0.000 claims description 13
- 239000010408 film Substances 0.000 claims description 11
- 238000001259 photo etching Methods 0.000 claims description 11
- 238000004528 spin coating Methods 0.000 claims description 11
- CSCPPACGZOOCGX-UHFFFAOYSA-N Acetone Chemical compound CC(C)=O CSCPPACGZOOCGX-UHFFFAOYSA-N 0.000 claims description 10
- 238000005530 etching Methods 0.000 claims description 10
- 238000001755 magnetron sputter deposition Methods 0.000 claims description 10
- 238000005260 corrosion Methods 0.000 claims description 9
- 230000007797 corrosion Effects 0.000 claims description 9
- 239000007788 liquid Substances 0.000 claims description 6
- 238000006243 chemical reaction Methods 0.000 claims description 5
- 150000002739 metals Chemical class 0.000 claims description 5
- 239000000126 substance Substances 0.000 claims description 5
- 238000001947 vapour-phase growth Methods 0.000 claims description 5
- 230000037303 wrinkles Effects 0.000 claims description 5
- 238000000137 annealing Methods 0.000 claims description 2
- 238000010438 heat treatment Methods 0.000 claims description 2
- 239000003960 organic solvent Substances 0.000 claims description 2
- 239000007789 gas Substances 0.000 claims 3
- 238000004070 electrodeposition Methods 0.000 claims 1
- 238000007740 vapor deposition Methods 0.000 claims 1
- 230000035945 sensitivity Effects 0.000 abstract description 5
- 229910021421 monocrystalline silicon Inorganic materials 0.000 abstract 1
- 229910052451 lead zirconate titanate Inorganic materials 0.000 description 28
- 238000001039 wet etching Methods 0.000 description 8
- DDFHBQSCUXNBSA-UHFFFAOYSA-N 5-(5-carboxythiophen-2-yl)thiophene-2-carboxylic acid Chemical compound S1C(C(=O)O)=CC=C1C1=CC=C(C(O)=O)S1 DDFHBQSCUXNBSA-UHFFFAOYSA-N 0.000 description 4
- 238000009835 boiling Methods 0.000 description 4
- 239000003518 caustics Substances 0.000 description 4
- 230000007423 decrease Effects 0.000 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 description 4
- 239000000463 material Substances 0.000 description 4
- 239000000203 mixture Substances 0.000 description 4
- 238000001020 plasma etching Methods 0.000 description 4
- 238000005229 chemical vapour deposition Methods 0.000 description 3
- 238000010586 diagram Methods 0.000 description 3
- 238000004088 simulation Methods 0.000 description 3
- 230000008878 coupling Effects 0.000 description 2
- 238000010168 coupling process Methods 0.000 description 2
- 238000005859 coupling reaction Methods 0.000 description 2
- 239000004411 aluminium Substances 0.000 description 1
- 229910052782 aluminium Inorganic materials 0.000 description 1
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 1
- 239000012080 ambient air Substances 0.000 description 1
- 230000005611 electricity Effects 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 230000001939 inductive effect Effects 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 229910021420 polycrystalline silicon Inorganic materials 0.000 description 1
- 229920005591 polysilicon Polymers 0.000 description 1
- 239000004065 semiconductor Substances 0.000 description 1
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Abstract
The present invention relates to a cantilever type vibrating diaphragm structure for microphones and loudspeakers and a preparation method thereof. Firstly, a layer of silicon nitride is deposited on a single crystal silicon substrate, the back surface of the silicon substrate is corroded, a back cavity is formed, a layer of silicon dioxide is deposited on silicon nitride, a metal Pt/Ti layer is sprayed in a radio frequency magnetic control mode, the metal Pt/Ti layer is photoetched, and a bottom layer electrode is formed; a PZT ferroelectric film is prepared on the Pt/Ti layer by a sol-gel method, a top layer electrode is prepared on the PZT ferroelectric film, one side is removed, and the cantilever type vibrating diaphragm structure of the present invention is obtained. The sensitivity and the acoustic output of microphones and loudspeakers integrated by the cantilever type vibrating diaphragm structure prepared by the present invention are obviously improved.
Description
The present invention relates to a kind of cantilever type diaphragm structure that is used for micro-microphone and loud speaker and preparation method thereof, belong to field of semiconductor devices.
Piezoelectric has power, signal of telecommunication coupled characteristic, can be used for the mutual conversion of power, the signal of telecommunication.Its principle as shown in Figure 1, upper and lower surface at piezoelectric membrane is made metal electrode, when behind z direction making alive V, power electric coupling characteristic according to piezoelectric, piezoelectric can produce strain in the x direction, because piezoelectric membrane is fixed on the substrate, so the strain on the x direction causes the disturb song of film in the z direction, thereby compress ambient air is finished the conversion of electroacoustic signal.In like manner, after the z direction added force signal (as acoustic pressure), film also can be disturbed song in the z direction, made the x direction produce strain, thereby produced electric charge in the upper and lower surface of piezoelectric, finished the conversion from sound to the electricity.Utilize this structure is can implementation structure simple, high performance, integrate microphone and speaker performance integrated micro-microphone of piezo-electric type and loudspeaker device.
At present, conventional microphone generally has the shortcoming that volume is big, price is high, and for the ratio of performance to price of improving microphone and microphone is developed to the direction of miniaturization, high performance, people have utilized the MEMS technology to make mini microphone more on silicon chip.The eighties researcher produces first piezoelectric micromotor microphone with the ZnO piezoelectric on silicon chip.After this, the researcher constantly improves the manufacture method and the performance of micro-microphone.Recently, the researcher of U.S. Berkeley has proposed a kind of cantilever type diaphragm structure of the ZnO of employing piezoelectric, see Fig. 2, micro-microphone and little loud speaker can be integrated on the same chip, can obtain higher sensitivity harmony output simultaneously based on this structure.Consult document " piezoelectric cantilever decline microphone and loud speaker ", " microelectromechanical systems ", (U.S.), 1996,5 (4): 238-242.
Because the piezoelectric coefficient d of ZnO piezoelectric
31Less, qualities such as the sound output of integrated micro-microphone and loadspeaker structure and sensitivity are desirable not enough.
The objective of the invention is to propose a kind of cantilever type diaphragm structure that is used for micro-microphone and loud speaker and preparation method thereof, this structure is utilized lead zirconate titanate (Pb
x(Zr
yTi
1-y) O
3, hereinafter to be referred as PZT) and ferroelectric is significantly higher than the piezoelectric modulus of ZnO, and its more excellent power electric coupling performance just makes to have more that the silica-based integrated micro-microphone of high sensitivity harmony output quality and the realization of loud speaker become possibility.
The preparation method of the cantilever type diaphragm structure that is used for micro-microphone and loud speaker that the present invention proposes, be made up of following each step:
(1) low-pressure chemical vapor phase deposition (LPCVD) one deck silicon nitride on monocrystalline substrate, the condition of LPCVD is 830 ℃ of temperature, pressure 90Pa, reacting gas are SiH
4With NH
3, the ratio of its volume is 8~5: 1, and deposition time changes with silicon nitride thickness, and the silicon nitride layer thickness range is 0.5~2 μ m.
(2) silicon substrate back side corrosion forms back of the body chamber, and corrosive liquid is the KOH solution of concentration 50%, and 50 ℃ of reaction temperatures, corrosion rate are about 1 μ m/min.
(3) deposit one layer thickness is the silicon dioxide of 3000~5000 on silicon nitride, and reacting gas is SiH
4And O
2, the ratio of its volume is 1: 2~3,500 ℃ of deposition temperatures.
(4) rf magnetron sputtering metal Pt/Ti layer, wherein Pt layer thickness scope is 500~1000 , Ti layer thickness scope is 50~100 , sputter frequency 13.56MHz, 120 ℃ of sputter temperature, photoetching metal Pt/Ti layer forms hearth electrode again, and wherein projection exposure is adopted in photoetching, metal Pt/Ti layer inductive couple plasma (ICP) method etching.
(5) on the Pt/Ti layer, prepare PZT ferroelectric thin film, PZT (Pb with sol-gel (sol-gel) method
x(Zr
yTi
1-y) O
3) component in: x=0.9~1.1, y=0.4~0.6, the thickness of PZT ferroelectric thin film is 0.5-2 μ m, can obtain corresponding thickness by the number of times that changes spin coating PZT colloidal sol.The wet film that obtains after each spin coating needs the The pre-heat treatment removal organic solvent through 380 ℃ and 800 ℃, at last pzt thin film is placed 900 ℃ environment annealing in process 30 minutes, obtains the PZT ferroelectric thin film.
(6) the positive glue of spin coating one deck on above-mentioned PZT ferroelectric thin film, rf magnetron sputtering metal Pt/Ti layer thereon after the photoetching, wherein Pt layer thickness scope is 500~1000 , Ti layer thickness scope is 50~100 .Sputter frequency 13.56MHz, 46 ℃ of sputter temperature were at room temperature soaked about 10 minutes with acetone again, had glue part metals Pt/Ti layer to send out wrinkle and peeled off, and can form the Pt/Ti top electrode.
(7) from the M point in front each layer film of etching down, remove a wherein side, the opposite side of reservation forms the cantilever diaphragm structure, and the length and width of cantilever design are 1000~2000 μ m.And the end of removing the PZT layer, make the equal in length of itself and top layer electrode, and become stepped with bottom electrode.Wherein pzt thin film adopts reactive ion etching, and reacting gas is SF
6And CF
4, its volume ratio is 1: 1, and gas flow is 25 ml/min, and power is 300 watts.Silicon dioxide layer is with having added ammonium fluoride (NH
4F) the HF solution of buffer carries out wet etching, and corrosion rate is about 2000 /min under 50 ℃ of conditions.The silicon nitride layer wet etching, corrosive agent is the H of boiling
3PO
4Solution, and adopt refluxed evaporator device corrosive liquid composition when preventing to operate to change, the corrosion rate of silicon nitride is about 100 /min.
The cantilever type diaphragm structure that is used for micro-microphone and loud speaker that the present invention proposes, successively by: the silicon dioxide layer of silicon substrate, silicon nitride layer, low temperature deposition, bottom Pt/Ti electrode, PZT ferroelectric thin film, top layer Pt/Ti electrode are arranged mutually and are formed.The length that silicon nitride layer wherein, the silicon dioxide layer of low temperature deposition, bottom Pt/Ti electrode, PZT ferroelectric thin film, top layer Pt/Ti electrode arrangement form is 1000~2000 μ m, stretches out from silicon substrate, forms cantilever design.In the bottom Pt/Ti electrode wherein, the Pt layer thickness is 500~1000 , and the Ti layer thickness is 50~100 .In the top layer Pt/Ti electrode wherein, Pt layer thickness scope is 500~1000 , and Ti layer thickness scope is 50~100 .
Adopt the ferroelectric cantilever type diaphragm structure of PZT of the present invention's preparation, integrated micro-microphone and loud speaker, its sensitivity harmony output is significantly improved than the micro-microphone and the loud speaker that adopt original material and structure.
Description of drawings:
Fig. 1 is the schematic diagram of piezoelectric cantilever diaphragm structure.
Fig. 2 is existing cantilever type diaphragm structure based on the ZnO piezoelectric.
Fig. 3 is the preparation process schematic diagram of PZT cantilever type diaphragm structure of the present invention.
Fig. 4 is a PZT cantilever type diaphragm structure schematic diagram of the present invention.
Among Fig. 1-3: 1 is the aluminium electrode, and 2 is ZnO piezoelectric film, and 3 is polysilicon electrode, 4 is the silicon dioxide layer of low temperature deposition, and 5 is silicon nitride layer, and 6 is the silicon dioxide layer of heat growth, 7 is silicon substrate, and 8 is top layer Pt/Ti electrode, and 9 is the PZT ferroelectric thin film, 10 is bottom Pt/Ti electrode, the 11st, part is removed at the edge of PZT ferroelectric thin film, and 12 is the edge removal part of bottom electrode, and 13 is that etching is removed part, 14 for removing side, and 15 are back of the body chamber.
Below in conjunction with accompanying drawing, introduce principle of the present invention and embodiment in detail.
The principle of foundation of the present invention is: ferroelectric material also has piezoelectric property with piezoelectric is the same, and the piezoelectric constant of ferroelectric material is much larger than piezoelectric.Replace piezoelectric ZnO with ferroelectric material PZT, can under the situation that adds the same electrical pressure, obtain the bigger Qu Weiyi that disturbs, thereby realize more high-quality integrated micro-microphone and loud speaker.
The cantilever type diaphragm structure that is used for micro-microphone and loud speaker that the present invention proposes, successively by: the silicon dioxide layer 4 of silicon substrate 7, silicon nitride layer 5, low temperature deposition, bottom Pt/Ti electrode 10, PZT ferroelectric thin film 9, top layer Pt/Ti electrode 8 are arranged mutually and are formed.It is 1000~2000 μ m that silicon nitride layer 5 wherein, the silicon dioxide layer 4 of low temperature deposition, bottom Pt/Ti electrode 10, PZT ferroelectric thin film 9, top layer Pt/Ti electrode 8 are arranged the length that forms, and stretches out from silicon substrate 7, forms cantilever design.
Introducing below is embodiments of the invention.
Embodiment 1: prepare each layer and be respectively the thick Pt/Ti/PZT/Pt/Ti/SiO of 0.05/0.005/1/0.05/0.005/0.5/1 μ m
2/ Si
3N
4The cantilever type diaphragm structure, the vibrating diaphragm length and width are respectively 1000 μ m.
(1) the thick silicon nitride of low-pressure chemical vapor phase deposition (LPCVD) one deck 1 μ m on monocrystalline substrate, the condition of LPCVD is 830 ℃ of temperature, pressure 90Pa, reacting gas SiH
4With NH
3The ratio of volume is 6: 1, and deposition time is about 3 hours;
(2) 50 ℃ down with 50% KOH solution from back side anisotropic etch silicon substrate about 5 hours, makes and carry on the back the chamber;
(3) at the silicon dioxide of front chemical vapor deposition 5000 , reacting gas is SiH
4And O
2, the ratio of its volume is 1: 2,500 ℃ of deposition temperatures;
(4) the metal Pt/Ti layer of rf magnetron sputtering 500/50 is made hearth electrode, negative glue photoetching, and ICP etching metal Pt/Ti layer forms hearth electrode;
(5) prepare the thick PZT ferroelectric thin film of 1 μ m, lead titanate-zirconate (Pb with eight spin coatings of sol-gel method
y(Zr
x, Ti
1-x) O
3) in component parameter be: x=0.53, y=1.06;
(6) the positive glue of spin coating one deck on the PZT ferroelectric thin film, after the photoetching thereon rf magnetron sputtering thickness be the metal Pt/Ti layer of 500/50 , sputter frequency 13.56MHz, 46 ℃ of sputter temperature, at room temperature soaked about 10 minutes again with acetone, there is glue part metals Pt/Ti layer to send out wrinkle and peels off, can form the Pt/Ti top electrode;
(7) from the M point in front each layer film of etching down, remove a wherein side, the opposite side of reservation forms the cantilever diaphragm structure, and the length and width of cantilever design are 1000 μ m, and wherein pzt thin film adopts reactive ion etching, and reacting gas is SF
6And CF
4Each 50%, gas flow is 25 ml/min, power is 300 watts, etch period needs 20 minutes approximately, silicon dioxide layer is with having added ammonium fluoride (NH
4F) the HF solution of buffer carries out wet etching, and 50 ℃ of corrosion temperatures need 2.5 minutes approximately.The silicon nitride layer wet etching, corrosive agent is the H of boiling
3PO
4Solution, and adopt refluxed evaporator device corrosive liquid composition when preventing to operate to change, etch period is about 100 minutes.
The one the second resonance frequencys and the output sound intensity level at the resonance frequency place that obtain this cantilever type micro-microphone through simulation, test are respectively; 2.33kHz, 65dB; 14.6kHz, 99dB.The low-frequency sensitive degree of cantilever type micro-microphone is 0.8mV/ μ bar.Decline the one the second resonance frequencys and the output sound intensity level at the resonance frequency place of loud speaker of the ZnO cantilever of same size is respectively: 2.75kHz, 46dB; 17.2kHz, 73dB.The low-frequency sensitive degree of cantilever type micro-microphone is 0.7mV/ μ bar.
Embodiment 2: prepare each layer and be respectively the thick Pt/Ti/PZT/Pt/Ti/SiO of 0.08/0.008/1.5/0.08/0.008/0.4/1.8 μ m
2/ Si
3N
4The cantilever type diaphragm structure, the vibrating diaphragm length and width are respectively 1500 μ m.
(1) the thick silicon nitride of low-pressure chemical vapor phase deposition (LPCVD) one deck 1.8 μ m on monocrystalline substrate, the condition of LPCVD is 830 ℃ of temperature, pressure 90Pa, reacting gas SiH
4With NH
3The ratio of volume is 5: 1, and deposition time is about 5 hours;
(2) 50 ℃ down with 50% KOH solution from back side anisotropic etch silicon substrate about 5 hours, makes and carry on the back the chamber;
(3) at the silicon dioxide of front chemical vapor deposition 4000 , reacting gas is SiH
4And O
2, the ratio of its volume is 1: 2.5,500 ℃ of deposition temperatures;
(4) the metal Pt/Ti layer of rf magnetron sputtering 800/80 is made hearth electrode, negative glue photoetching, and ICP etching metal Pt/Ti layer forms hearth electrode;
(5) prepare the thick PZT ferroelectric thin film of 1.5 μ m, lead titanate-zirconate (Pb with ten spin coatings of sol-gel method
y(Zr
x, Ti
1-x) O
3) in component parameter be: x=0.45, y=1;
(6) the positive glue of spin coating one deck on the PZT ferroelectric thin film, after the photoetching thereon rf magnetron sputtering thickness be the metal Pt/Ti layer of 800/80 , sputter frequency 13.56MHz, 46 ℃ of sputter temperature.At room temperature soaked about 10 minutes again, have glue part metals Pt/Ti layer to send out wrinkle and peel off, can form the Pt/Ti top electrode with acetone;
(7) from the M point in front each layer film of etching down, remove a wherein side, the opposite side of reservation forms the cantilever diaphragm structure, and the length and width of cantilever design are 1500 μ m, and wherein pzt thin film adopts reactive ion etching, and reacting gas is SF
6And CF
4Each 50%, gas flow is 25 ml/min, power is 300 watts, etch period needs 30 minutes approximately.Silicon dioxide layer is with having added ammonium fluoride (NH
4F) the HF solution of buffer carries out wet etching, and 50 ℃ of corrosion temperatures need 2 minutes approximately.The silicon nitride layer wet etching, corrosive agent is the H of boiling
3PO
4Solution, and adopt refluxed evaporator device corrosive liquid composition when preventing to operate to change, etch period is about 180 minutes.
The one the second resonance frequencys and the output sound intensity level at the resonance frequency place that obtain this cantilever type micro-microphone through simulation, test are respectively: 1.38kHz, 64dB; 8.6kHz, 96dB.The low-frequency sensitive degree of cantilever type micro-microphone is 1.3mV/ μ bar.Decline the one the second resonance frequencys and the output sound intensity level at the resonance frequency place of loud speaker of the ZnO cantilever of same size is respectively: 1.62kHz, 43dB; 10.17kHz, 82dB.The low-frequency sensitive degree of cantilever type micro-microphone is 1.1mV/ μ bar.
Embodiment 3: prepare each layer and be respectively the thick Pt/Ti/PZT/Pt/Ti/SiO of 0.1/0.01/0.5/0.1/0.01/0.3/0.5 μ m
2/ Si
3N
4The cantilever type diaphragm structure, the vibrating diaphragm length and width are respectively 2000 μ m.
(1) the thick silicon nitride of low-pressure chemical vapor phase deposition (LPCVD) one deck 0.5 μ m on monocrystalline substrate, the condition of LPCVD is 830 ℃ of temperature, pressure 90Pa, reacting gas SiH
4With NH
3The ratio of volume is 8: 1, and deposition time is about 1.5 hours;
(2) 50 ℃ down with 50% KOH solution from back side anisotropic etch silicon substrate about 5 hours, makes and carry on the back the chamber;
(3) at the silicon dioxide of front chemical vapor deposition 3000 , reacting gas is SiH
4 -And O
2, the ratio of its volume is 1: 3,500 ℃ of deposition temperatures;
(4) the metal Pt/Ti layer of rf magnetron sputtering 1000/100 is made hearth electrode, negative glue photoetching, and ICP etching metal Pt/Ti layer forms hearth electrode;
(5) prepare the thick PZT ferroelectric thin film of 0.5 μ m, lead titanate-zirconate (Pb with four spin coatings of sol-gel method
y(Zr
x, Ti
1-x) O
3) in component parameter be: x=0.58, y=0.94;
(6) the positive glue of spin coating one deck on the PZT ferroelectric thin film, after the photoetching thereon rf magnetron sputtering thickness be the metal Pt/Ti layer of 1000/100 , sputter frequency 13.56MHz, 46 ℃ of sputter temperature.At room temperature soaked about 10 minutes again, have glue part metals Pt/Ti layer to send out wrinkle and peel off, can form the Pt/Ti top electrode with acetone;
(7) from the M point in front each layer film of etching down, remove a wherein side, the opposite side of reservation forms the cantilever diaphragm structure, and the length and width of cantilever design are 2000 μ m, and wherein pzt thin film adopts reactive ion etching, and reacting gas is SF
6And CF
4Each 50%, gas flow is 25 ml/min, power is 300 watts, etch period needs 10 minutes approximately.Silicon dioxide layer is with having added ammonium fluoride (NH
4F) the HF solution of buffer carries out wet etching, and 50 ℃ of corrosion temperatures need 1.5 minutes approximately.The silicon nitride layer wet etching, corrosive agent is the H of boiling
3PO
4Solution, and adopt refluxed evaporator device corrosive liquid composition when preventing to operate to change, etch period is about 50 minutes.
The one the second resonance frequencys and the output sound intensity level at the resonance frequency place that obtain this cantilever type micro-microphone through simulation, test are respectively: 1.0kHz, 63dB; 6.5kHz, 102dB.The low-frequency sensitive degree of cantilever type micro-microphone is 1.7mV/ μ bar.Decline the one the second resonance frequencys and the output sound intensity level at the resonance frequency place of loud speaker of the ZnO cantilever of same size is respectively: 1.22kHz, 42dB; 7.65kHz, 72dB.The low-frequency sensitive degree of cantilever type micro-microphone is 1.5mV/ μ bar.
Claims (4)
1, a kind of preparation method who is used for the cantilever type diaphragm structure of micro-microphone and loud speaker is characterized in that, this method comprises following each step:
(1) low-pressure chemical vapor phase deposition one deck silicon nitride on monocrystalline substrate, the condition of vapor deposition is 830 ℃ of temperature, pressure 90Pa, reacting gas are SiH
4With NH
3, the ratio of its volume is 8~5: 1, making silicon nitride layer thickness is 0.5~2 μ m;
(2) silicon substrate back side corrosion forms back of the body chamber, and corrosive liquid is the KOH solution of concentration 50%, and 50 ℃ of reaction temperatures, corrosion rate are about 1 μ m/min
(3) deposit one layer thickness is the silicon dioxide of 3000~5000 on silicon nitride, and reacting gas is SiH
4And O
2, the ratio of the volume of two kinds of gases is 1: 2~3,500 ℃ of deposition temperatures;
(4) rf magnetron sputtering metal Pt/Ti layer, wherein the Pt layer thickness is 500~1000 , the Ti layer thickness is 50~100 , sputter frequency 13.56MHz, 120 ℃ of sputter temperature, photoetching metal Pt/Ti layer again, to form bottom electrode, remove the marginal portion, make it become stepped with silicon dioxide layer;
(5) on the Pt/Ti layer, prepare PZT ferroelectric thin film, PZT (Pb with sol-gel process
x(Zr
yTi
1-y) O
3) component in: x=0.9~1.1, y=0.4~0.6, the wet film that obtains after each spin coating is through the The pre-heat treatment removal organic solvent of 380 ℃ and 800 ℃, at last pzt thin film placed 900 ℃ environment annealing in process 30 minutes, and the thickness that obtains the PZT ferroelectric thin film is 0.5-2 μ m;
(6) preparation top layer electrode on above-mentioned PZT ferroelectric thin film: the positive glue of spin coating one deck at first, carry out photoetching selectively according to the top layer electrode position, rf magnetron sputtering metal Pt/Ti layer thereon again, sputter frequency 13.56MHz, 46 ℃ of sputter temperature, wherein Pt layer thickness scope is 500~1000 , Ti layer thickness scope is 50~100 , at room temperature soaked 10 minutes again, have glue part metals Pt/Ti layer to send out wrinkle and peel off, promptly form Pt/Ti top layer electrode with acetone;
(7) from the M point in front each layer film of etching down, remove a wherein side, the opposite side that keeps forms the cantilever diaphragm structure, the length that makes cantilever design is 1000~2000 μ m, and the end of removing the PZT layer, make the equal in length of itself and top layer electrode, and become stepped, be the cantilever type diaphragm structure that is used for micro-microphone and loud speaker of the present invention with bottom electrode.
2, a kind of cantilever type diaphragm structure that is used for micro-microphone and loud speaker, it is characterized in that, this structure successively by: the silicon dioxide layer of silicon substrate, silicon nitride layer, low temperature deposition, bottom Pt/Ti electrode, PZT ferroelectric thin film, top layer Pt/Ti electrode are arranged mutually and are formed, the film that the silicon dioxide layer of described silicon nitride layer, low temperature deposition, bottom Pt/Ti electrode, PZT ferroelectric thin film, top layer Pt/Ti electrode arrangement form, stretch out from silicon substrate, forming length is the cantilever design of 1000~2000 μ m.
3, structure as claimed in claim 2 is characterized in that, in the wherein said bottom Pt/Ti electrode, the Pt layer thickness is 500~1000 , and the Ti layer thickness is 50~100 .
4, structure as claimed in claim 2 is characterized in that, in the wherein said top layer Pt/Ti electrode, Pt layer thickness scope is 500~1000 , and Ti layer thickness scope is 50~100 .
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Publication number | Priority date | Publication date | Assignee | Title |
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US11924608B2 (en) | 2021-08-11 | 2024-03-05 | Shenzhen Shokz Co., Ltd. | Microphone |
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