CN103139691B - Micro-electromechanical system (MEMS) silicon microphone utilizing multi-hole signal operation instruction (SOI) silicon bonding and manufacturing method thereof - Google Patents
Micro-electromechanical system (MEMS) silicon microphone utilizing multi-hole signal operation instruction (SOI) silicon bonding and manufacturing method thereof Download PDFInfo
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- 238000004519 manufacturing process Methods 0.000 title claims abstract description 15
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Abstract
The invention provides a micro-electromechanical system (MEMS) silicon microphone utilizing multi-hole signal operation instruction (SOI) silicon bonding and a manufacturing method thereof. The MEMS silicon microphone comprises a multi-hole back pole plate silicon substrate and a single crystal silicon vibrating diaphragm placed above the multi-hole back plate silicon substrate. The MEMS silicon microphone is characterized in that the multi-hole back plate silicon substrate and the single crystal silicon vibrating diaphragm serve as two pole plates of a microphone capacitor and are integrated in a bonding mode through a silicon bonding process. The multi-hole back pole plate silicon substrate is provided with a back pole plate metal electrode, a sound aperture and a back cavity, the single crystal silicon vibrating diaphragm is provided with a metal electrode and a small protruded column, and the vibrating diaphragm electrode and the back pole plate respectively serve as output signal leading-out ends of two pole plates of the microphone capacitor to be used for being in electric connection with a complementary metal oxide semiconductor (CMOS) signal amplifying circuit. The single crystal silicon vibrating diaphragm is supported by a silicon oxide layer to be suspended above the multi-hole back plate silicon substrate, and an air gap exists between the single crystal silicon vibrating diaphragm and the multi-hole back plate silicon substrate, and the multi-hole back plate silicon substrate, the single crystal silicon vibrating diaphragm and the air gap form a capacitance structure. The MEMS silicon microphone utilizing multi-hole SOI silicon bonding and the manufacturing method thereof are simple in process, high in product sensitivity, good in consistency and high in yield rate.
Description
Technical field
The present invention relates to a kind of capacitive-type silicon microphone and preparation method thereof, particularly disclose a kind of MEMS silicon microphone adopting porous SOI Si-Si bonding, belong to the technical field of silicon microphone.
Background technology
Mike's wind energy is converted into the corresponding signal of telecommunication the voice signal of people, is widely used in mobile phone, computer, telephone set, camera and video camera etc.Traditional electret capacitor microphone adopts Teflon as vibration film, and can not bear the high temperature nearly 300 degree of reflow soldering of printed circuit board technique, thus can only separate with the assembling of integrated circuit, independent hand assembled, considerably increases production cost.
The MEMS(Microelectromechanical Systems of nearly 30 years) development of technology, particularly based on the development of silicon MEMS technology, achieve microminiaturization and the low cost of many transducers (as pressure sensor, accelerometer, gyroscope etc.).MEMS silicon microphone starts industrialization, in the application of high-end handsets, replaces traditional electret capacitor microphone gradually.
MEMS microphone mainly still adopts capacitive principle, is made up of, has the spacing of several microns between vibration film and back pole plate a vibration film and back pole plate, forms capacitance structure.After high-sensitive vibration film experiences outside audio frequency sound pressure signal, change the distance between vibration film and back pole plate, thus form capacitance variations.Connect the change that cmos amplifier changes into capacitance variations voltage signal after MEMS microphone, then after amplifying, become electricity output.
The voice sound pressure signal of people is very faint, and vibration film must be very sensitive.Vibrating membrane adopts conventional semiconducter process-deposit to obtain usually, and material can adopt multiple or multilayer material to obtain (such as doped polycrystalline silicon, metal and silicon nitride composite membrane etc.).Due to thermal coefficient of expansion difference and the high-temperature technology of material, the vibration film after preparation has residual stress in various degree, greatly have impact on the sensitivity of vibration film.So, during with polysilicon as vibration film, generally can adopt additional anneal technique after the production, regulate residual stress to drop to minimum; If with silicon nitride as vibration film, in the preparation by regulating the ratio between reacting gas to reduce residual stress.But adopt little to the effect reducing residual stress in this way, and repeatability is bad, realizes also comparatively complicated.In addition, also can adopt the mechanical structure changing vibration film, general plate vibration film be changed into line film, epistasis, or on vibration film, cuts small groove, thus reach the object reducing residual Ying Li ﹑ increase sensitivity.But the method changing vibration film structure can cause complicated process of preparation, increase cost, reduce yield.
Back pole plate, except being formed except electric capacity with vibration film, also has the frequency band controlling microphone, reduces the functions such as acoustic noise.It needs to have certain rigidity, can not because of the vibration of outside or acoustic pressure and deformation.In addition, it is the perforation of several microns to thousands of diameters that general design also need be prepared hundreds of on back pole plate, is used for regulating the frequency band of microphone and reducing acoustic noise.
Summary of the invention
The object of the invention is to overcome the deficiencies in the prior art, provide a kind of and adopt MEMS silicon microphone of porous SOI Si-Si bonding and preparation method thereof, with simplified manufacturing technique, and yield and the sensitivity of capacitance type minitype silicon microphone can be improved.
The present invention is achieved in that a kind of MEMS silicon microphone and the manufacture method thereof that adopt porous SOI Si-Si bonding, comprise porous back pole plate silica-based and be positioned at the monocrystalline silicon vibrating diaphragm of the described silica-based top of porous back pole plate, it is characterized in that: the silica-based and monocrystalline silicon vibrating diaphragm of described porous back pole plate, as the two-plate of microphone electric capacity, is bonded to one through Si-Si bonding process; The manufacture method of described microphone comprises the steps:
A, the back pole plate adopting conductivity good are silica-based;
B, on above-mentioned back pole plate is silica-based, DRIE etches some blind holes, and form porous back pole plate silica-based, the blind hole etched is the acoustic aperture of microphone;
C, on above-mentioned porous back pole plate is silica-based thermal oxidation go out one deck silicon oxide layer;
D, provide conductivity good monocrystalline silicon as vibration film substrate, and thermal oxidation goes out one deck silicon oxide layer on the substrate;
E, by above-mentioned vibration film substrate and back pole plate Bonded on Silicon Substrates;
F, above-mentioned vibration film substrate attenuation is become vibration film, i.e. monocrystalline silicon vibrating diaphragm;
The above-mentioned vibration film of g, plasma etching, etching runs through vibration film, the silica below etched portions, forms the outline of required small convex pillar;
H, plasma etching run through above-mentioned vibration film and under silica, expose the face of the silica-based upper deposit metal electrodes of back pole plate;
I, in above-mentioned device surface LPCVD doped polycrystalline silicon;
J, the polysilicon removing the silica-based back side of back pole plate in above-mentioned device and silica;
K, at above-mentioned device upper surface depositing metal layers;
L, etching run through the metal level of above-mentioned device and lower polysilicon thereof, formation metal electrode and small convex pillar;
M, deposit one deck PECVD silica at above-mentioned device upper surface;
N, above-mentioned device porous back pole plate silica-based back side DRIE etch the back of the body chamber until porous back pole plate silica-based on silica, the back of the body chamber be positioned at immediately below acoustic aperture;
O, wet method remove the silica that in above-mentioned device, PECVD generates;
P, wet method remove the silica between the silica-based back of the body chamber of porous back pole plate in above-mentioned device and acoustic aperture and the silica below vibration film oscillating component, release vibration film.
The MEMS silicon microphone of the employing porous SOI Si-Si bonding that the inventive method obtains, is characterized in that: porous back pole plate is silica-based all to conduct electricity well, as the two-plate of microphone electric capacity with monocrystalline silicon vibrating diaphragm; Deposit back pole plate polysilicon on porous back pole plate is silica-based, back pole plate polysilicon deposits back pole plate metal electrode, back pole plate metal electrode is through back pole plate polysilicon and the silica-based electrical connection of porous back pole plate; Porous back pole plate is silica-based is provided with acoustic aperture and back of the body chamber, and acoustic aperture and back of the body chamber communicate; Monocrystalline silicon vibrating diaphragm is provided with small convex pillar, and the material of small convex pillar is polysilicon and metal level, and small convex pillar avoids monocrystalline silicon vibrating diaphragm and the silica-based adhesive of porous back pole plate; Monocrystalline silicon vibrating diaphragm deposits vibrating diaphragm polysilicon, vibrating diaphragm polysilicon deposits vibrating diaphragm metal electrode, vibrating diaphragm metal electrode is through vibrating diaphragm polysilicon and the electrical connection of monocrystalline silicon vibrating diaphragm; Vibrating diaphragm metal electrode and back pole plate electrode all adopt Al/Cu alloy and TiN material, are respectively the output signal exit of microphone electric capacity two-plate, are used for realizing being electrically connected with cmos signal amplifying circuit; Monocrystalline silicon vibrating diaphragm and porous back pole plate silica-based through Si-Si bonding process be bonded to one, monocrystalline silicon vibrating diaphragm is supported by silicon oxide layer and is suspended from the silica-based top of porous back pole plate, monocrystalline silicon vibrating diaphragm and porous back pole plate silica-based between be provided with air gap, porous back pole plate is silica-based, monocrystalline silicon vibrating diaphragm and air gap form capacitance structure.Described monocrystalline silicon vibrating diaphragm utilizes the thinning rear formation of monocrystalline silicon piece, and described monocrystalline silicon vibrating diaphragm thickness is 2 ~ 3 microns.Described monocrystalline silicon vibrating diaphragm and porous back pole plate silica-based between air gap formed by wet etching silica.
According to technical scheme of the present invention, MEMS silicon microphone of the present invention, the silica-based thickness of described porous back pole plate is 400 ~ 450 μm, and its conduction is as a pole of electric capacity, and vibration film (i.e. monocrystalline silicon vibrating diaphragm) conduction is as another pole of electric capacity; Porous back pole plate is silica-based is provided with tens acoustic aperture, and described acoustic aperture is positioned at immediately below vibration film, and aperture is about 40 μm; Acoustic aperture has back of the body chamber, makes the easier through porous back pole plate of acoustic aperture silica-based; Vibration film is positioned at the top of acoustic aperture and covers whole acoustic aperture face, vibration film is provided with small convex pillar, described small convex pillar can be reduced in the possibility that in vibrating diaphragm wet chemical release process process, vibration film and back pole plate are pulled together, and obtains after vibration film is thinning by monocrystalline silicon piece; Vibration film by silica be supported on back pole plate silica-based on, described silica can realize vibration film and the silica-based electric insulation of back pole plate simultaneously, and vibration film and back pole plate silica-based between the air gap degree of depth also determined by this silicon oxide thickness; Vibration film and back pole plate is silica-based above all deposits metal pad, metal pad is used for realizing being electrically connected with cmos signal amplifying circuit.
The invention has the beneficial effects as follows: the silica-based vibration film being provided with monocrystalline silicon of porous back pole plate of the present invention, i.e. monocrystalline silicon vibrating diaphragm, it is legal in porous back pole plate Bonded on Silicon Substrates by Si prediction, the monocrystalline silicon vibrating diaphragm of conduction and the silica-based formation capacitance structure of porous back pole plate; To be that monocrystalline silicon piece is thinning form the monocrystalline silicon vibrating diaphragm of conduction, and its conductivity is good, and as a pole of electric capacity, and its residual stress is little and consistency good, thus can improve sensitivity and the yield of microphone; Monocrystalline silicon vibrating diaphragm is provided with small convex pillar, and small convex pillar can be reduced in monocrystalline silicon vibrating diaphragm wet chemical release process process and the possibility of monocrystalline silicon vibrating diaphragm and the silica-based adhesive of porous back pole plate when using, and improves the yield of microphone further; The silica-based conductivity of porous back pole plate is good, and as another pole of electric capacity, porous back pole plate is silica-based is provided with acoustic aperture.When sound acts on monocrystalline silicon vibrating diaphragm, external cmos circuit changes the capacitance variations that causes by detecting monocrystalline silicon vibrating diaphragm thus exports corresponding voice signal.The inventive method obtains that the production technology of microphone is simple, highly sensitive, cost is low, consistency good, yield is high.
Accompanying drawing explanation
Fig. 1 is the structural representation of MEMS silicon microphone side of the present invention.
Fig. 2 is the structural representation of MEMS silicon microphone opposite side of the present invention.
Fig. 3 is the sectional structure schematic diagram of MEMS silicon microphone of the present invention.
Fig. 4 is the schematic cross-section after forming acoustic aperture in the inventive method on back pole plate is silica-based.
Fig. 5 is the schematic cross-section in the inventive method after back pole plate silicon substrate surface generates silica.
Fig. 6 is the schematic cross-section in the inventive method after vibrating diaphragm silicon substrate surface generation silica.
Fig. 7 is the schematic cross-section forming device in the inventive method after the silica-based and silica-based Si-Si bonding of vibrating diaphragm of back pole plate.
Fig. 8 be in the inventive method by silica-based for vibrating diaphragm thinning be the schematic cross-section after vibrating diaphragm.
Fig. 9 is the schematic cross-section in the hole etched on vibrating diaphragm and silica in the inventive method for deposition small convex pillar.
Figure 10 etches the schematic cross-section that vibrating diaphragm and silica expose the face of the silica-based upper deposit metal electrodes of back pole plate in the inventive method.
Figure 11 is the schematic cross-section in device surface LPCVD doped polycrystalline silicon in the inventive method.
Figure 12 is the schematic cross-section after the polysilicon at the silica-based back side of removal devices back pole plate in the inventive method and silica.
Figure 13 is the schematic cross-section at device upper surface depositing metallic films in the inventive method.
Figure 14 etches the schematic cross-section that metal film and polysilicon obtain electrode and projection in the inventive method.
Figure 15 is the schematic cross-section depositing one deck PECVD silica in the inventive method at device upper surface.
Figure 16 is the schematic cross-section going out to carry on the back chamber in the inventive method at device back-etching.
Figure 17 is the schematic cross-section of the silica removing upper surface in the inventive method.
Figure 18 removes the silica between the silica-based back of the body chamber of back pole plate and acoustic aperture and the silica below vibration film oscillating component in the inventive method, discharge the schematic cross-section of vibrating diaphragm.
In figure: 1, porous back pole plate is silica-based; 2, monocrystalline silicon vibrating diaphragm; 3, acoustic aperture; 4, chamber is carried on the back; 5, air gap; 6, back pole plate metal electrode; 7, back pole plate polysilicon; 8, small convex pillar; 9, insulating medium layer; 10, vibrating diaphragm metal electrode; 11, vibrating diaphragm polysilicon.
Embodiment
Below in conjunction with concrete drawings and Examples, the invention will be further described.
1 ~ accompanying drawing 18 with reference to the accompanying drawings, the present invention includes that porous back pole plate is silica-based 1, monocrystalline silicon vibrating diaphragm 2, acoustic aperture 3, back of the body chamber 4, air gap (polar plate spacing) 5, back pole plate metal electrode 6, back pole plate polysilicon 7, small convex pillar 8, insulating medium layer (i.e. silicon oxide layer) 9, vibrating diaphragm metal electrode 10, vibrating diaphragm polysilicon 11.
With reference to the accompanying drawings 3, MEMS silicon microphone of the present invention comprises porous back pole plate and the supporter of the monocrystalline silicon vibrating diaphragm 2 that is positioned on back pole plate and monocrystalline silicon vibrating diaphragm.In the present invention, back pole plate comprises porous back pole plate silica-based 1, and porous back pole plate silica-based 1 is provided with acoustic aperture 3 and back of the body chamber 4.Acoustic aperture 3 is uniformly distributed in the top in back of the body chamber 4, and communicates with back of the body chamber 4.LPCVD doped polycrystalline silicon on porous back pole plate silica-based 1, form back pole plate polysilicon 7, back pole plate polysilicon 7 is doped polycrystalline silicon, and conductivity is good.Back pole plate polysilicon 7 is coated with back pole plate metal electrode 6, back pole plate metal electrode 6 is electrically connected with porous back pole plate silica-based 1 by back pole plate polysilicon 7.The aperture of acoustic aperture 3 is 40 microns, and silica-based 1 thickness of the porous back pole plate as microphone back pole plate is 400 ~ 450 microns; The size of acoustic aperture, quantity and position set on demand, are as the criterion with extremely low acoustic noise can obtain required spirit quick degree ﹑ bandwidth.
Monocrystalline silicon vibrating diaphragm 2 forms by monocrystalline silicon is thinning, and monocrystalline silicon vibrating diaphragm 2 conductivity is good, as a pole of microphone electric capacity.Monocrystalline silicon vibrating diaphragm 2 is supported by insulating medium layer (i.e. silicon oxide layer) 9, is suspended on the top of acoustic aperture 3, and forms air gap 5 between porous back pole plate silica-based 1.The thickness of silicon oxide layer 9 determines the degree of depth of air gap 5, and the insulation property of simultaneous oxidation silicon layer 9 ensure that the electric insulation of monocrystalline silicon vibrating diaphragm 2 and porous back pole plate silica-based 1.Monocrystalline silicon vibrating diaphragm 2 is provided with small convex pillar 8, and small convex pillar can reduce the possibility that monocrystalline silicon vibrating diaphragm 2 and porous back pole plate silica-based 1 are pulled together.The material of small convex pillar 8 is polysilicon and metal level, with electrode synchronous forming.The electrode part of monocrystalline silicon vibrating diaphragm 2 has polysilicon 11, and polysilicon 11 is doped polycrystalline silicon, and conductivity is good.Polysilicon 11 is coated with vibrating diaphragm metal electrode 10, vibrating diaphragm metal electrode 10 is electrically connected with monocrystalline silicon vibrating diaphragm 2 by vibrating diaphragm polysilicon 11.The material of the metal level on back pole plate metal electrode 6, vibrating diaphragm metal electrode 10 and small convex pillar is Al/Cu alloy+TiN, adopts first depositing metal layers, then dry etching goes out the capable one-tenth of required figure.
Fig. 4 ~ accompanying drawing 18 with reference to the accompanying drawings, the present invention adopts the manufacture method of the MEMS silicon microphone of porous SOI Si-Si bonding to comprise following processing step:
A, the back pole plate providing conductivity good are silica-based, the silica-based pole as electric capacity of back pole plate, and its thickness is 400 ~ 450 microns;
B, the blind hole (i.e. acoustic aperture 3) that DRIE etching 50 ~ 100 microns is dark on above-mentioned back pole plate is silica-based, form porous back pole plate silica-based 1, the blind hole etched is the acoustic aperture of microphone.As shown in Figure 4: blind hole uses DRIE etching, and the degree of depth is 50 ~ 100 microns, and the aperture of blind hole is 40 microns;
The silicon oxide layer 12 of c, thermal oxidation about 1 micron on above-mentioned porous back pole plate silica-based 1.As shown in Figure 5: silicon oxide layer 12 is for the silica-based Si-Si bonding of porous back pole plate silica-based 1 and vibrating diaphragm, and this silicon oxide layer can as stop-layer during DRIE etching back of the body chamber 4 below;
D, the vibrating diaphragm providing conductivity good are silica-based, and the silicon oxide layer 13 of thermal oxidation about 1.5 micron thickness.As shown in Figure 6: silicon oxide layer 13 is for silica-based 1 Si-Si bonding silica-based with back pole plate of vibrating diaphragm; Silicon oxide layer 13 synthesizes silicon oxide layer 9 with the silicon oxide layer 12 in step c after Si-Si bonding;
E, form device by silica-based for vibrating diaphragm with silica-based 1 Si-Si bonding of back pole plate.As shown in Figure 7: adopt Si-Si bonding process by silica-based for vibrating diaphragm integral with back pole plate Bonded on Silicon Substrates;
F, by silica-based for the vibrating diaphragm on above-mentioned device thinning.As shown in Figure 8: by silica-based for the vibrating diaphragm on above-mentioned device thinning formation vibration film, i.e. monocrystalline silicon vibrating diaphragm 2, the thickness of monocrystalline silicon vibrating diaphragm 2 is 2 ~ 3 microns;
G, on monocrystalline silicon vibrating diaphragm 2 and silicon oxide layer 9, etch aperture 14.As shown in Figure 9: dry etching aperture on above-mentioned monocrystalline silicon vibrating diaphragm 2, aperture runs through monocrystalline silicon vibrating diaphragm 2, the silicon oxide layer 9 that the position dry etching of aperture exposes on monocrystalline silicon vibrating diaphragm 2, the degree of depth of etching oxidation silicon layer 9 about 1.5 microns, the profile of the aperture 14 of etching is the outline of small convex pillar 8;
H, on above-mentioned device, etching runs through monocrystalline silicon vibrating diaphragm 2 and silicon oxide layer 9 subregion, exposes the silica-based upper region for polysilicon 7 and back pole plate metal electrode 6 on deposition back pole plate of porous back pole plate.As shown in Figure 10: dry etching runs through the subregion of above-mentioned monocrystalline silicon vibrating diaphragm 2, etch the silicon oxide layer 9 run through below it simultaneously, expose the backplate area for deposition back pole plate polysilicon 7 and back pole plate metal electrode 6, etching technics etches the outline defining monocrystalline silicon vibrating diaphragm 2 simultaneously;
I, at above-mentioned device surface LPCVD doped polysilicon layer 15.As shown in Figure 11: polysilicon layer thicknesses is 0.5 micron, and polycrystalline silicon is good;
J, the polysilicon removing the above-mentioned device back side and silica.As shown in Figure 12: polysilicon layer and the thermal silicon oxide layer of removing the above-mentioned device back side, utilize photoresist to do front protecting, dry etching removes polysilicon layer, and dry method or wet method remove silicon oxide layer, and dry method is plasma etching, and wet etching liquid is BOE;
K, at above-mentioned device front sputtering sedimentation metal level 16.As shown in Figure 13: at above-mentioned device front sputtering sedimentation metal level 16, the material of metal level 16 is Al/Cu alloy and TiN, TiN covers Al/Cu alloy surface protection Al/Cu alloy and is not corroded, and the thickness of Al/Cu alloy is 2 microns, and the thickness of TiN is 0.1 micron;
L, at above-mentioned device front etches polycrystalline silicon layer 15 and metal level 16.As shown in Figure 14: utilize photoresist to do mask, RIE etching runs through metal level 16, plasma etching or RIE etching run through polysilicon layer 15, polysilicon 11 on polysilicon 7, small convex pillar 8, vibrating diaphragm metal electrode 10, vibrating diaphragm on etching rear formation back pole plate metal electrode 6, back pole plate, back pole plate metal electrode 6 and vibrating diaphragm metal electrode 10 are for being connected with external cmos circuit;
M, at above-mentioned device front PECVD silicon oxide layer 17.As shown in Figure 15: silicon oxide layer 17 thickness is 1 micron, as the protective layer in front during etching back of the body chamber 4, PECVD silicon oxide layer is more loose, more easily removes when wet method is removed;
N, etch back of the body chamber 4 at above-mentioned device back side DRIE.As shown in Figure 16: utilize DRIE technique to etch back of the body chamber 4, back of the body chamber 4 is positioned at immediately below acoustic aperture 3, the degree of depth about 300 ~ 350 microns in back of the body chamber 4, etching stopping when running into thermal silicon oxide layer 12 during DRIE etching;
O, remove the silicon oxide layer 17 of above-mentioned device.As shown in Figure 17: utilize wet etching to remove silicon oxide layer 17, wet etching liquid is that BOE, PECVD silicon oxide layer 17 is more loose, when removing in a wet process, thermal silicon oxide layer 15 can not be removed simultaneously completely;
P, the silicon oxide layer 12 removing part directly over back of the body chamber 4 and silicon oxide layer 13.As shown in Figure 18: the silicon oxide layer 12 directly over wet method removal back of the body chamber and silicon oxide layer 13; form air gap 5; back of the body chamber 4 communicates with acoustic aperture 3; silicon oxide layer 9 is formed after etching; silicon oxide layer 9 supports monocrystalline silicon vibrating diaphragm 2 and is suspended from above porous back pole plate silica-based 1; wet etching liquid is BOE; during etching, device front utilizes thick photoresist to protect; the thickness of photoresist is more than 15 microns; adopting thick glue can prevent etching rear monocrystalline silicon vibrating diaphragm 2 is drawn onto on porous back pole plate silica-based 1; thick glue can utilize acetone and dry method to remove, and discharges monocrystalline silicon vibrating diaphragm 2.
During work, between the monocrystalline silicon vibrating diaphragm 2 of MEMS silicon microphone of the present invention and porous back pole plate silica-based 1, form capacitance structure.When there is sound outside, sound can produce active force to monocrystalline silicon vibrating diaphragm 2, and the surface of monocrystalline silicon vibrating diaphragm 2 is subject to active force and can produces corresponding deformation.When deformation occurs monocrystalline silicon vibrating diaphragm 2, also can there is corresponding change in the capacitance structure formed between monocrystalline silicon vibrating diaphragm 2 with porous back pole plate silica-based 1, can detect corresponding voice signal by external CMOS ASIC signal amplification circuit.
Back pole plate of the present invention realizes on porous back pole plate silica-based 1, and the diameter design of acoustic aperture 3 is 40 microns, and acoustic aperture 3 is communicated with air by back of the body chamber 4, reduces the process costs of etching acoustic aperture 3.Monocrystalline silicon thin film 2 forms by single crystal silicon substrate is thinning, simplifies manufacture craft and reduces the stress of vibrating membrane, the consistency that improve product and yield.The two poles of the earth of electric capacity are taken on by porous back pole plate silica-based 1 and monocrystalline silicon vibrating diaphragm 2, further simplify technique.Silicon oxide layer 9 ensure that the electric insulation of monocrystalline silicon vibrating diaphragm 2 and porous back pole plate silica-based 1, simultaneous oxidation silicon layer 9 support monocrystalline silicon vibrating diaphragm 2 be suspended from back pole plate silica-based on, the thickness of the thickness silica layer 9 of air gap 5 determines, air gap 5 is obtained by etching oxidation silicon 12 and silica 13, and technique is simple.Monocrystalline silicon vibrating diaphragm 2 is provided with small convex pillar 8, and small convex pillar 8 can reduce the possibility that monocrystalline silicon vibrating diaphragm 2 and porous back pole plate silica-based 1 are pulled together.Technique of the present invention all adopts maturation process, and technique is simple.Inventive microphone is highly sensitive, consistency good and it is high to produce yield, and this microphone can be packaged as a whole with ASIC, uses SMT technique to carry out follow-up printed circuit board (PCB) attachment.
Claims (4)
1. one kind adopts the manufacture method of the MEMS silicon microphone of porous SOI Si-Si bonding, the device of MEMS silicon microphone comprises porous back pole plate silica-based (1) and is positioned at the monocrystalline silicon vibrating diaphragm (2) of the silica-based top of described back pole plate, it is characterized in that: described back pole plate silica-based (1) and vibrating diaphragm (2), as the two-plate of microphone electric capacity, are bonded to one through Si-Si bonding process; The manufacture method of described microphone comprises the steps:
A, the back pole plate adopting conductivity good are silica-based;
B, on above-mentioned back pole plate is silica-based, DRIE etches some blind holes, and this blind hole is the acoustic aperture of microphone;
C, on above-mentioned back pole plate is silica-based thermal oxidation go out one deck silicon oxide layer;
D, provide conductivity good monocrystalline silicon as vibration film substrate, and thermal oxidation goes out one deck silicon oxide layer on the substrate;
E, by above-mentioned vibration film substrate and back pole plate Bonded on Silicon Substrates;
F, above-mentioned vibration film substrate attenuation is become vibration film;
G, adopt plasma etching to etch aperture on above-mentioned vibration film, aperture runs through vibration film, on vibration film the position of aperture etch below the part of silica, form the outline of required small convex pillar;
H, plasma etching run through above-mentioned vibration film and under silica, expose the face of the silica-based upper deposit metal electrodes of back pole plate;
I, adopt LPCVD method doped polycrystalline silicon at above-mentioned device surface;
J, the polysilicon removing the silica-based back side of back pole plate in above-mentioned device and silica;
K, adopt sputtering method depositing metal layers at above-mentioned device upper surface;
L, etching run through the metal level of above-mentioned device and lower polysilicon thereof, formation metal electrode and small convex pillar;
M, deposit at above-mentioned device upper surface the silica that one deck adopts PECVD method to generate;
N, the back pole plate of above-mentioned device silica-based back side DRIE etch the back of the body chamber until back pole plate silica-based on silica, the back of the body chamber be positioned at immediately below acoustic aperture;
O, wet method remove the silica that in above-mentioned device, PECVD generates;
P, wet method remove the silica between the silica-based back of the body chamber of back pole plate in above-mentioned device and acoustic aperture and the silica below vibration film oscillating component, release vibration film.
2. the MEMS silicon microphone of the employing porous SOI Si-Si bonding obtained by manufacture method described in claim 1, it is characterized in that: adopt porous back pole plate silica-based (1) and monocrystalline silicon vibrating diaphragm (2) as the two-plate of microphone electric capacity, described porous back pole plate silica-based (1) and the good conductivity of the equal tool of monocrystalline silicon vibrating diaphragm (2); Silica-based (1) deposits back pole plate polysilicon (7) to back pole plate, back pole plate polysilicon (7) deposits back pole plate metal electrode (6), and back pole plate metal electrode (6) is through back pole plate polysilicon (7) and back pole plate silica-based (1) electrical connection; Back pole plate silica-based (1) is provided with acoustic aperture (3) and back of the body chamber (4), and acoustic aperture (3) and back of the body chamber (4) communicate; Vibrating diaphragm (2) is provided with small convex pillar (8), and small convex pillar (8) is made up of polysilicon and metal level, and described metal-layer structure is that TiN covers the formation of made of Al-Cu alloy surface, and small convex pillar (8) avoids the adhesive of vibrating diaphragm (2) and back pole plate silica-based (1); Vibrating diaphragm (2) deposits vibrating diaphragm polysilicon (11), vibrating diaphragm polysilicon (11) deposits vibrating diaphragm metal electrode (10), vibrating diaphragm metal electrode (10) is through vibrating diaphragm polysilicon (11) and vibrating diaphragm (2) electrical connection; Vibrating diaphragm metal electrode (10) and back pole plate electrode (6) all adopt made of Al-Cu alloy and TiN to form, cover made of Al-Cu alloy surface protection made of Al-Cu alloy by TiN not to be corroded, be respectively the output signal exit of microphone electric capacity two-plate, be used for realizing being electrically connected with cmos signal amplifying circuit; Vibrating diaphragm (2) and back pole plate silica-based (1) are bonded to one through Si-Si bonding process, vibrating diaphragm (2) is supported the top being suspended from back pole plate silica-based (1) by silicon oxide layer (9), be provided with air gap (5) between vibrating diaphragm (2) and back pole plate silica-based (1), back pole plate silica-based (1), vibrating diaphragm (2) and air gap (5) form capacitance structure.
3. according to the MEMS silicon microphone of the employing porous SOI Si-Si bonding described in claim 2, it is characterized in that: utilize monocrystalline silicon piece thinning rear as vibrating diaphragm (2), described vibrating diaphragm (2) thickness is 2 ~ 3 microns.
4. the MEMS silicon microphone of employing porous SOI Si-Si bonding according to claim 3, is characterized in that: the air gap (5) between described vibrating diaphragm (2) and back pole plate silica-based (1) is formed by wet etching silica.
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