CN100596241C - Single-crystal silicon micro-machinery manufactured capacitor type microphone and method for manufacturing same - Google Patents
Single-crystal silicon micro-machinery manufactured capacitor type microphone and method for manufacturing same Download PDFInfo
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- CN100596241C CN100596241C CN200410042603A CN200410042603A CN100596241C CN 100596241 C CN100596241 C CN 100596241C CN 200410042603 A CN200410042603 A CN 200410042603A CN 200410042603 A CN200410042603 A CN 200410042603A CN 100596241 C CN100596241 C CN 100596241C
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Abstract
A capacitance microphone for monocrystalline micro-mechanical working, which contains flexible plane board, rigidity plane board and support frame part for forming internal air isolation, and made ofepitaxy monocrystalline layer, the working process containing medium pattern epitaxy growth and monocrystalline growth, the formation of microstructure adopting the micro-mechanical working of monocrystalline selective formation and corrosion, said invention adopts homogeneous monocrystalline material to eliminate the problem resulting from thermal-mismatching by dissimilar material.
Description
Condenser type sonic sensor or microphone are widely used in consumer products and instrumentation, such as telephone device, and tape recorder, video camera, speech amplifier, and hearing aids etc.Silicon micromachining technique has been used to make various microphones, and its operation principle, can be accompanyed or follow the sound signal that transmits and vibrate because a cube electrode of capacitor places on the flexible flat based on variable capacitor.The use of silicon micromachining technique mainly can bring following benefit: (1) capacitor can stand the thermal shock up to 100 degrees centigrade; (2) control precision of raising capacitor sizes; (3) be convenient to the yardstick of reduction of device and other element; (4) be beneficial to and carry out volume production, to reduce production costs; And (5) combine sonic sensor and integrated circuit easily, becomes system on a chip.All these benefit final effects all are the ratios of performance to price that improves microphone.
Made [M.Royer since first sonic sensor from people such as Royer, J.O.Holmen, M.A.Wurm, O.S.Aadland, and M.Glenn, ZnO on Si integrated acoustic sensor, Sensors and Actuators, 4, (1983), 357-362], many reports all are to make sonic sensor [W.Kuhnel, and G.Hess with two silicon chip combinations, Micro-machined subminiaturecondenser microphones in silicon, Sensors and Actuators A, 32 (1992), 560-564].People such as Scheeper began with single silicon wafer to manufacture sonic sensor in 1991, its method is to form back side stiffener plate with sacrifice layer and electrogilding, and at the inner flexible flat [P.R.Scheeper that forms of silicon chip, W.Olthuis, and P.Bergveld, Fabrication of a subminiaturesilicon condenser microphone using the sacrificial layer technique, Proc.6th Int.Conf.Solid-State Sensors and Actuators (Transducers ' 91), SanFrancisco, USA, June 24-28,1991,408-411].People such as Pedersen report carries out the microphone [M.Pedersen that micromachined is produced to applying the polyimides that overlays on the silicon chip that is integrated with voltage changer and preamplifier, W.Olthui s, P.Bergveld, Integrated siliconcapacitive microphone with frequency-modulated digital output Sensors﹠amp; Actuators A-Physical.n 3, Sep 15 (1998), 267-275].People such as Bernstein report is used in combination surface micromachined and the body micromachining technology is produced highly sensitive sonic sensor [A.E.Kabir, R.Bashir, J.Bernstein, J.De Santis, R.Mathews, J.O.O ' Boyle, C.Bracken, Very High Sensitivity Acoustic Transducers withThin P+ Membrane and Gold Back Plate, Sensors and Actuators-A, Vol.78, issue 2-3, pp.138-142,17th Dec.1999.].
The Electret Condencer Microphone of silicon micro mechanical processing has experienced the change of several generations, and its most frequent and topmost effort concentrates on the thickness that reduces capacitor flexible flat and air buffer always, and reduces the driving voltage that it adds.Though the performance of the microphone of silicon micro mechanical processing always constantly is improved, and runs into several recurrent difficult problems through regular meeting.One of difficult problem adopts heterojunction material to make flexible flat and stiffener plate, can produce the thermal mismatch stress of impelling device degradation.Two of difficult problem, when making flexible flat with monocrystalline silicon, its reduced thickness usually is restricted.Three of difficult problem, owing to lack the expendable material of corrosion automatic stop, the air buffer lateral length is difficult to accurate control.Difficult problem like that waits suddenly that all developing new technology is solved, and the place of this purpose of the present invention just.
Main purpose of the present invention, just provide a kind of Electret Condencer Microphone that all processes by single-crystal-silicon micro mechanical, the flexible flat of its capacitor and stiffener plate all are material with monocrystalline silicon, and every problem that is caused by the thermal mismatch stress between the different materials can fundamentally be eliminated.
Another object of the present invention just provides a kind of Electret Condencer Microphone that is all processed by single-crystal-silicon micro mechanical, and the natural stress of the flexible flat of its capacitor can be adjusted to the required optimum value of work by the doping content that changes silicon materials.
The 3rd purpose of the present invention, just provide a kind of Electret Condencer Microphone that all processes by single-crystal-silicon micro mechanical, its sound wave afferent pathway aperture area can be less than the flexible flat area of capacitor, so that dwindling of capacitor lateral length is unlikely the restriction that is subjected to the access portal area.
The 4th purpose of the present invention just provides a kind of Electret Condencer Microphone that is all processed by single-crystal-silicon micro mechanical, and the flexible flat thickness of its capacitor not only can accurately be controlled, and can be easy to be reduced in 1 micron.
The 5th purpose of the present invention just provides a kind of Electret Condencer Microphone that is all processed by single-crystal-silicon micro mechanical, and the lateral length of the air buffer of its capacitor can accurately be controlled.
The 6th purpose of the present invention just provides a kind of Electret Condencer Microphone that is all processed by single-crystal-silicon micro mechanical, and its capacitor can be easy to be incorporated on the same monocrystalline substrate with its signal processing circuit.
General objective of the present invention just provides a kind of Electret Condencer Microphone that is all processed by single-crystal-silicon micro mechanical, and its ratio of performance to price can have bigger raising.
Summarize in fact, the capacitor of the microphone that is all processed by single-crystal-silicon micro mechanical of the present invention is mainly by monocrystalline substrate, and the monocrystalline silicon flexible flat has the monocrystalline silicon stiffener plate of through hole, and is made up of the support frame that all or part of monocrystalline silicon constitutes.The periphery of flexible flat is fixed within the monocrystalline substrate, the sound wave afferent pathway that its back side forms towards the part monocrystalline silicon of diging up substrate.Stiffener plate is located on the flexible flat, by support frame from around support, support within the frame and accompany air buffer between two flat boards.Support the upper face of frame to be coated with composite dielectric film, make and realize the electricity isolation between flexible flat and the stiffener plate.Two metal electrodes are arranged in the peripheral region of stiffener plate, and the monocrystalline silicon region that splits by groove is connected with stiffener plate with flexible flat respectively.
The monocrystalline silicon flexible flat is formed by the first epitaxy single-crystal silicon layer that is grown on the first porous monocrystalline silicon trap.The first porous monocrystalline silicon trap is by monocrystalline substrate being placed HF solution carry out anodic oxidation, the monocrystalline silicon region generation anodic attack on part top layer being formed.The desired thickness of the first porous monocrystalline silicon trap is realized by doping depth control or anodizing time control.
The lattice constant of porous monocrystalline silicon is usually greater than the monocrystalline silicon that forms this porous monocrystalline silicon, thereby is grown in the epitaxy single-crystal silicon layer that has on the porous monocrystalline silicon layer with the same doping content of monocrystalline substrate and is in because the extended state that lattice mismatch causes.And the lattice constant of doped monocrystalline silicon reduces and increases along with its doping content, thereby can the lattice mismatch stress of the epitaxy single-crystal silicon layer that is grown on the porous monocrystalline silicon layer is compensated by regulating doping content, makes device be in best stress state.
Stiffener plate is formed by the second epitaxy single-crystal silicon layer that is grown on the second porous monocrystalline silicon trap.The formation of the second porous monocrystalline silicon trap is carried out in two steps, and the first step is mixed the upper area of the first epitaxy single-crystal silicon layer, and second step was carried out anodic oxidation in HF solution, the upper area that mixes is transformed into the porous monocrystalline silicon trap.
Support the moulding of frame to form by the monocrystalline silicon region that the epitaxial lateral of many merging is crossed prosperous growth.When carrying out the selective epitaxial monocrystalline silicon growing on the medium pattern, the prosperous growth of this mistake can appear at the upper face of dielectric layer fringe region, and Sheng Chang monocrystalline silicon region can be to the inboard lateral magnification of dielectric layer thus.Support frame also can cross the monocrystalline silicon of prosperous growth and the polysilicon that deposits purely forms jointly on dielectric layer by epitaxial lateral, this be because epitaxial lateral to cross the monocrystalline silicon region of prosperous growth narrow usually, the monocrystalline silicon region of crossing prosperous growth by wall scroll is difficult to obtain the moulding than the support frame of broad.
Polysilicon layer on the second epitaxy single-crystal silicon layer and the compound medium layer forms simultaneously, just is respectively formed on multi-hole mono-crystal layer and the dielectric layer.
After the second epitaxy single-crystal silicon layer is opened the hole, just can selective corrosion remove the second porous monocrystalline silicon trap, thereby can under stiffener plate, form air buffer.
The sound wave afferent pathway is formed by the corrosion monocrystalline substrate.Adopt the technology of selective corrosion or timing corrosion, make corrosion end at the suitable position of the first porous monocrystalline silicon trap.The first porous monocrystalline silicon trap is removed in selective corrosion then, makes to be released by the remaining coating portion of the first epitaxy single-crystal silicon layer, becomes the unsettled flexible flat in two sides.
Overview of the present invention can be illustrated with following each figure.
Fig. 1, be the cross-sectional view of the Electret Condencer Microphone of silicon micro mechanical processing the preceding.
Fig. 2, partly excise perspective view for the Electret Condencer Microphone that all processes provided by the invention by single-crystal-silicon micro mechanical.
Fig. 3, be the cross-sectional view that the Electret Condencer Microphone that is all processed by single-crystal-silicon micro mechanical provided by the invention then forms in the processing through the first step, the first porous monocrystalline silicon trap is formed within the monocrystalline substrate shown in the figure.
Fig. 4, for the Electret Condencer Microphone that all processes by single-crystal-silicon micro mechanical provided by the invention at the cross-sectional view that then forms through the processing of second step, the first epitaxy single-crystal silicon layer growth shown in the figure is included in the first porous monocrystalline silicon trap surface on the monocrystalline substrate surface.
Fig. 5, for the Electret Condencer Microphone that all processes by single-crystal-silicon micro mechanical provided by the invention at the cross-sectional view that then forms through the processing of the 3rd step, the second porous monocrystalline silicon trap is formed within the first epitaxy single-crystal layer shown in the figure.
Fig. 6, for the Electret Condencer Microphone that all processes by single-crystal-silicon micro mechanical provided by the invention at the cross-sectional view that then forms through the processing of the 4th step, the second epitaxy single-crystal silicon layer growth is in the first epitaxy single-crystal silicon surface shown in the figure, be included in the second porous monocrystalline silicon trap surface, meanwhile at complex media bar surface deposition polysilicon layer.
Fig. 7, for the Electret Condencer Microphone that all processes by single-crystal-silicon micro mechanical provided by the invention in the cross-sectional view that then forms through the processing of the 5th step, the metal electrode pattern that on the second epitaxy single-crystal layer, forms shown in the figure.
Fig. 8, for the Electret Condencer Microphone that all processes by single-crystal-silicon micro mechanical provided by the invention at the cross-sectional view that then forms through the processing of the 6th step, the second epitaxial monocrystalline silicon layer region that is in second porous monocrystalline silicon trap top shown in the figure has equally distributed through hole, the second porous monocrystalline silicon trap becomes air buffer after being corroded and removing, and the perforate silicon area of its top becomes stiffener plate.
Fig. 9, for the Electret Condencer Microphone that all processes by single-crystal-silicon micro mechanical provided by the invention at the cross-sectional view that then forms through the processing of the 7th step, be formed by etching shown in the figure, as the groove of sound wave afferent pathway, its bottom is remaining monocrystalline substrate layer.
Figure 10, for the Electret Condencer Microphone that all processes by single-crystal-silicon micro mechanical provided by the invention at the cross-sectional view that then forms through the processing of the 8th step, the remaining monocrystalline substrate layer and the first porous monocrystalline silicon trap are removed in selective corrosion shown in the figure, thereby form the unsettled flexible flat in two sides.
Figure 11, making the cross-sectional view that the back forms for the Electret Condencer Microphone that is all processed by single-crystal-silicon micro mechanical provided by the invention through CMOS, cmos circuit shown in the figure is formed in the second epitaxy single-crystal silicon layer in addition of microphone capacitor zone.
Before elaborating the microphone that all processes of the present invention by single-crystal-silicon micro mechanical, the simple Electret Condencer Microphone of introducing a kind of typical the preceding silicon micro mechanical processing as shown in Figure 1.This microphone comprises silicon substrate 101, dielectric layer 102, monocrystalline silicon layer 103, polysilicon layer 104, sound wave afferent pathway 105, flexible flat 106, air buffer 107,108, the first groups of oxide next doors 109 of the stiffener plate of perforate and 110, second group of oxide next door 111 and 112, and electrode pair 113 and 114.Flexible flat 106 is formed by SOI (silicon layer on the dielectric layer) material, 1 to 3 micron of its thickness.Stiffener plate 108 forms 10 to 20 microns of its thickness by polysilicon layer.3 to 5 microns of air buffers are behind the erosion removal sacrifice layer and the space of vacateing.Be not difficult to find out that by Fig. 1 what be used as sacrifice layer is silicon oxide layer, its part that retains becomes first group of oxide next door 109 and 110.
The Electret Condencer Microphone that all processes by single-crystal-silicon micro mechanical of the present invention as shown in Figure 2, its basic comprising is roughly similar to the Electret Condencer Microphone of silicon micro mechanical processing the preceding.This microphone consists of monocrystalline substrate 201, the first epitaxy single-crystal silicon layers 202, the second epitaxy single-crystal silicon layers 203, dielectric layer 204, sound wave afferent pathway 205, flexible flat 206, air buffer 207 has the stiffener plate 208 of through hole and electrode pair 209 and 210.
After carrying out carefully Fig. 2 and Fig. 1 relatively, be not difficult to find out between the Electret Condencer Microphone of two kinds of silicon micro mechanicals processing and still have obviously difference.One of difference, the open-celled rigid flat board of microphone of the present invention is made by monocrystalline silicon, and the open-celled rigid flat board of microphone is made by polysilicon the preceding.Two of difference, the air buffer of microphone of the present invention is formed by erosion removal monocrystalline silicon, and the air buffer of microphone is formed by the erosion removal silica the preceding.Three of difference, the electricity between two flat boards of microphone of the present invention are isolated by relatively thinner compound medium layer realization, and the electricity between two flat boards of microphone is isolated by thicker silica realization the preceding.Four of difference, the maximum secting area of the sound wave afferent pathway of microphone of the present invention can be less than the area of flexible flat, and the maximum secting area of microphone sound wave afferent pathway must be greater than the area of flexible flat the preceding.Five of difference, microphone of the present invention easily and its signal processing circuit be integrated on the same plane of silicon chip, microphone and its signal processing circuit are integrated on the Different Plane of silicon chip the preceding.Exactly because produced above-mentioned difference, all targets of the present invention are just put into practice.
Below with reference to Fig. 3 to Figure 11, be described in detail the manufacture process of the Electret Condencer Microphone that all processes by single-crystal-silicon micro mechanical of the present invention.
For in monocrystalline substrate 301, forming by porous monocrystalline silicon trap 303 shown in Figure 3, at first must be ready to a monocrystalline substrate, its conduction type, the crystal orientation, and resistivity all do not have to be strict with, but generally tends to adopt P-type doped monocrystalline silicon sheet, and the crystal orientation is (100) direction, electrical resistivity range is within 1 to 10 ohm-cm, and the silicon chip two sides all needs through polishing.Making begins to form the compound medium layer 302 that is combined into by silica and silicon nitride with low-pressure vapor phase chemical deposition (LPCVD) technology on the monocrystalline substrate surface, and the thickness of silica and silicon nitride layer is respectively 500 dusts and 2000 dusts.Then carry out photoetching corrosion and form the anodic oxidation window of 200 to 2000 microns of some lateral lengths, the removal of silica is carried out wet etching, the removal CF of silicon nitride with the HF solution of dilution
4Gas carries out dry etching.Two chambers chemical reaction pond is adopted in anodic oxidation, is separated into two Room by monocrystalline silicon piece in the pond, and the opposing end surface of two Room is provided with platinum electrode.Electrolyte is 49%HF: C
2H
5OH (2: 1) solution, anodic current density is controlled at 5 to 20mA/cm
2In the scope.Anodic oxidation is limited in the anodic oxidation window of opening on single crystalline substrate 301 surfaces to be carried out, and forms the first porous monocrystalline silicon trap 303 of 200 to 2000 microns of some lateral lengths thus in single crystalline substrate 301, as shown in Figure 3.The first porous monocrystalline silicon trap, 303 degree of depth are controlled to be 10 to 20 microns, make growth rate according to experiment, by the required degree of depth of time acquisition of calculating the anodic oxidation experience
Make second step of microphone of the present invention, erosion removal monocrystalline substrate surface residual silicon nitride and silicon oxide layer before this then under 400 ℃ of temperature, in oxygen atmosphere, carry out the first porous monocrystalline silicon trap 303 that generates 1 hour oxidation processes.Its effect is to generate the thick oxide layer of 20 to 30 dusts on the hole wall of porous monocrystalline silicon, stops with this subsiding of loose structure taken place in high-temperature process subsequently.Then carry out the epitaxy single-crystal silicon growth in chemical vapor deposition stove, reactant gas source is SiH
2Cl
2And H
2, reaction temperature is 950 to 1050 ℃.The first epitaxy single-crystal silicon layer 304 that growth obtains covers whole monocrystalline substrate surface, comprises the first porous monocrystalline silicon trap, 303 surfaces, as shown in Figure 4.The representative value of epitaxy layer thickness is 3 to 5 microns, and the representative value of resistivity is 1 to 10 ohm-cm, and doping type is not subjected to strict restriction, but tends to identically with monocrystalline substrate, is the P-type.
Make the 3rd step of microphone of the present invention, be on the first epitaxy single-crystal silicon layer 304, to form the compound medium layer 305 of another silica and silicon nitride, and carry out the anodic oxidation window that photoetching corrosion forms 200 to 2000 microns of some lateral lengths.This shelters pattern and injects as ion earlier and shelter, and injects ion with anode oxidation window and carries out selective doping, and implantation dosage is 1 to 5x10
15/ cm
2, the doping type tendency is identical with the first epitaxy single-crystal silicon layer, is the P-type.Carry out annealing in process at 1000 ℃ then, the depths of doped region scope to the first epitaxy single-crystal silicon layer advanced, and produce dark 2.5 to 4.5 microns, mean impurity concentration is 10
18To 10
19/ cm
3Doped region, and the thickness of its remaining not doped region has only 0.5 to 1.5 micron.Under above-mentioned identical condition, carry out anodic oxidation then, the monocrystalline silicon of doped region is transformed into porous monocrystalline silicon, in the first epitaxy single-crystal silicon layer 304, to form the second porous monocrystalline silicon trap 306 that some Fig. 3 mark.Be noted that the second porous monocrystalline silicon trap 306 must be located in the first porous monocrystalline silicon layer 303 directly over.Be noted that simultaneously owing to the thickness that has formed the corresponding site of the second porous monocrystalline silicon trap, 306, the first epitaxy single-crystal silicon layers 304 is reduced, thereby form as the 307 epitaxy single-crystal silicon thin layers that indicated.Generally speaking, the thickness of epitaxy single-crystal silicon thin layer 307 is 0.5 to 1.5 micron, the acquisition of this thickness realizes by the degree of depth of the control second porous monocrystalline silicon trap 306, and the degree of depth of the second porous monocrystalline silicon trap 306 is by the propelling degree of depth decision of ion implantation doping layer.
In the 4th step of making, allow the above-mentioned identical low thermal oxidation of the second porous monocrystalline silicon trap, 306 experience handle earlier, and adopt above-mentioned identical technology on the first epitaxy single-crystal silicon layer, to form above-mentioned identical silica and silicon nitride compound medium layer.Then compound medium layer is carried out photoetching corrosion, remove the compound medium layer on most of first epitaxy single-crystal silicon layer, only stay at least one complex media bar 308 in the peripheral region of the second porous monocrystalline silicon trap, the width of medium strip is 20 to 100 microns.Then carry out epitaxial growth under above-mentioned identical condition, produce the second epitaxy single-crystal silicon layer, its thickness is 10 to 20 microns, and whether mixing does not all have to be strict with doping type.Just be noted that when 306 superficial growths of the first porous monocrystalline silicon trap obtain the second porous monocrystalline silicon layer 309, obtain the single crystalline layer 310a that epitaxial lateral is crossed prosperous growth in the superficial growth of the edge of compound medium layer bar 308.If the complex media bar than broad, then obtains polysilicon layer 310b at the centre of compound medium layer bar 308 surface deposition.Other position superficial growth in the first epitaxy single-crystal silicon surface obtains epitaxy single-crystal silicon layer 311, as shown in Figure 6.
In the 5th step of making, be used to form metal electrode pattern as shown in Figure 7.For this reason, first deposited by electron beam evaporation technology forms the chromium layer of thick 1000 dusts on the second epitaxy single-crystal silicon layer and polysilicon layer, and the deposited by electron beam evaporation technology forms the gold layer of thick 5000 dusts again.Carry out photoetching corrosion then and form electrode pattern as 312 and 313 signs.Be noted that this pattern must be fit to carry out subsequently the requirement that encapsulation (surface mountingpackage) is settled on the surface.Then carry out Alloying Treatment, between the second epitaxy single-crystal silicon layer and metal level, to form ohmic contact at 300 to 350 ℃.
The 6th step of making is that the through hole that penetrates epitaxial loayer is opened in 309 subregions of the second epitaxy single-crystal silicon layer, and the erosion removal second porous monocrystalline silicon trap 306.Through hole forms and adopts deep trouth reactive ion etching (DRIE) technology, and etchant gas is SF
6And C
4F
8Through hole comprises two parts, a part be in the first and second porous monocrystalline silicon traps 303 and 306 directly over 309 parts of the second epitaxy single-crystal silicon layer, 20 to 100 microns in aperture, 20 to 200 microns of hole Center Gap are evenly distributed on whole opening area.Another part is the deep trouth of two groups of sealings, 20 to 40 microns of groove widths, and one group of sealing deep trouth is separated polysilicon region on above-mentioned epitaxy single-crystal silicon layer aperture area and the compound medium layer and the second epitaxial monocrystalline silicon layer region on every side, as 316 signs.Another group sealing deep trouth is partitioned into a zone (not marking the figure) from the second epitaxial monocrystalline silicon layer region around the aperture area, its other zone with the second epitaxy single-crystal silicon layer is separated, and only link to each other with the first epitaxy single-crystal silicon layer 304 of its bottom.Use 49%HF: 30%H then
2O
2(5: 1) solution corrosion is removed the second porous monocrystalline silicon trap 306, thereby forms the stiffener plate 314 and the air buffer 315 of perforate.Be stressed that 49%HF: 30%H
2O
2(5: 1) solution only corrodes porous monocrystalline silicon, and to the epitaxy single-crystal silicon layer 307 that remains through the anodic oxidation attenuate by the first epitaxy single-crystal silicon layer without any corrosiveness.Porous monocrystalline silicon also can with the thin silicon oxide of erosion removal hole wall surface, be used 1 to 5%KOH solution, erosion removal porous monocrystalline silicon under room temperature then earlier with the HF solution immersion of dilution.The KOH solution of this dilution is very weak to the monocrystalline silicon corrosive power, can not influence the epitaxy single-crystal silicon layer 307 that will keep.
The 7th step of making is the back side corrosion pit from monocrystalline substrate, to form the sound wave afferent pathway basically.Must form the thick silicon nitride layer 317 of 2000 to 3000 dusts at the back side of monocrystalline substrate with the LPCVD technology earlier for this reason.Silicon nitride layer 317 is carried out photoetching corrosion can be to the window of monocrystalline substrate depths corrosion to form, and its lateral length can be less than the lateral length of the first porous monocrystalline silicon trap.Corroding silicon nitride is with above-mentioned identical dry etching technology.Carry out the method using fast wet corrosion subsequently, etchant solution is the aqueous solution of 40%KOH, and corrosion temperature is 60 ℃.The control etching time makes the bottom 319 of etch pit 318 still keep about 10 to 20 microns thickness, as shown in Figure 9.What be careful is that corrosion is entered in the first porous monocrystalline silicon trap, 303 zones.
In the 7th step of making, can adopt two kinds of schemes.First scheme is to carry out wet etching at a slow speed earlier, and corrosive agent is 49%HF: HNO
3: CH
3COOH (1: 3: 5 to 8) solution, corrosion temperature is a room temperature.The control etching time is removed above-mentioned quick corrosion and is carried over monocrystalline substrate thin layer 319, and and then corrosion is deep in the porous monocrystalline silicon layer 303, but deep scope is controlled in 3 to 5 microns.Use 49%HF: 30%H at last
2O
2(1: 5) solution carries out selective corrosion, thoroughly removes remaining porous monocrystalline silicon layer 303, makes it become cavity 320, and discharges the first epitaxy single-crystal silicon layer 307 that is thinned, and makes it become the unsettled gentle shape flat board 321 in two sides, as shown in figure 10.
Alternative plan is to carry out the selectivity dry etching with the reactive ion etching technology, and etchant gas is SF
6Or SF
6/ C
4F
8, this etchant gas only corrodes monocrystalline silicon, and does not corrode the porous monocrystalline silicon through slight oxidation, thereby corrosion can terminate on porous monocrystalline silicon layer 303 interfaces automatically.Use 49%HF: 30%H then
2O
2(1: 5) solution carries out wet etching, removes porous monocrystalline silicon trap 303, makes it become cavity 320, discharges the first epitaxy single-crystal silicon layer 307 that is thinned, and makes it become the unsettled gentle shape flat board 321 in two sides, still as shown in figure 10.
Shown in Figure 11, be the making step that forms cmos circuit 322 at the second epitaxy single-crystal silicon layer, 310 positions.This procedure of processing can be inserted between step 4 and the step 5 carries out.As shown in figure 11, cmos circuit 322 is produced on the left-hand component of monocrystalline substrate 301, and the material that directly is used for making cmos circuit 322 is the zone, position of the second epitaxy single-crystal silicon layer 311.This part epitaxy single-crystal silicon layer is directly to begin to grow from monocrystalline substrate 301 surfaces by the appropriate section of the first epitaxy single-crystal silicon layer 304, thereby is the top-quality zone of monocrystalline silicon.This cmos circuit mainly comprises dc voltage changer and preamplifier, the CMOS fabrication techniques of available standards.After finishing making, strengthen vapour deposition (PECVD) technology with plasma and form the thick 1 micron phosphor silicon oxide protective layer 323 of mixing, so as in manufacturing process subsequently protection cmos circuit 322, it can be damaged.
What narrate above is the preferred plan of implementing the Electret Condencer Microphone that is all processed by single-crystal-silicon micro mechanical of the present invention; this scheme is made amendment and adjusted; professional and technical personnel for same domain is easily, but this modification and adjustment can not exceed the protection range of claim of the present invention.
Claims (12)
1, a kind of Electret Condencer Microphone of single-crystal-silicon micro mechanical processing, its architectural feature comprises:
A monocrystalline substrate;
A sound wave afferent pathway of opening in monocrystalline substrate inside;
The flexible unitary silicon flat board that thick 0.5 to 1.5 micron and a lateral length are 200 to 2000 microns, the edge is fixed on monocrystalline substrate inside, and the back side is towards the sound wave afferent pathway;
One is high 2 to 5 microns, the main support frame that constitutes by monocrystalline silicon, and the bottom surface combines with the upper face of flexible unitary silicon plate edge part, and upper face is coated with the composite dielectric film of thick 2000 to 3000 dusts;
One thick 10 to 20 microns rigidity monocrystalline silicon flat board has 20 to 100 microns of lateral lengths, the equally distributed through hole that Center Gap is 20 to 200 microns, and the lower surface at edge combines with the composite dielectric film of the upper face of supporting frame;
A thick air buffer of 2 to 5 microns is between flexible unitary silicon flat board and the rigidity monocrystalline silicon flat board, and is centered on by the support frame that mainly is made of monocrystalline silicon; And
One group of metal electrode is in the neighboring area of rigidity monocrystalline silicon flat board, and dull and stereotyped with flexible unitary the silicon respectively and dull and stereotyped realization of rigidity monocrystalline silicon is electrically connected.
2, according to the Electret Condencer Microphone of the described single-crystal-silicon micro mechanical of claim 1 processing, its architectural feature also comprises and being integrated on the described monocrystalline substrate, is used for handling the integrated circuit of the signal of telecommunication of microphone generating.
3, according to the Electret Condencer Microphone of the described single-crystal-silicon micro mechanical processing of claim 1, it is characterized in that described flexible unitary silicon flat board is formed by the epitaxy single-crystal silicon layer that is grown in porous monocrystalline silicon trap surface.
4, according to the Electret Condencer Microphone of the described single-crystal-silicon micro mechanical processing of claim 1, it is characterized in that the monocrystalline silicon layer that the moulding of described support frame is crossed prosperous growth by the horizontal extension of some merging forms separately.
5, the Electret Condencer Microphone of processing according to the described single-crystal-silicon micro mechanical of claim 1, it is characterized in that, the monocrystalline silicon layer that the moulding of described support frame is crossed prosperous growth by the wall scroll horizontal extension forms, and deposits polysilicon layer on the described dielectric film that is positioned at described support frame upper face.
6, according to the Electret Condencer Microphone of the described single-crystal-silicon micro mechanical processing of claim 1, it is characterized in that described stiffener plate is formed by the epitaxy single-crystal silicon layer that is grown on the porous monocrystalline silicon trap.
7, according to the Electret Condencer Microphone of the described single-crystal-silicon micro mechanical processing of claim 1, it is characterized in that the release of described flexible flat is to realize by eroding its porous monocrystalline silicon trap that depends on.
8, according to the Electret Condencer Microphone of the described single-crystal-silicon micro mechanical processing of claim 1, it is characterized in that the release of described stiffener plate is to realize by eroding its porous monocrystalline silicon trap that depends on.
9, according to the Electret Condencer Microphone of the described single-crystal-silicon micro mechanical processing of claim 1, it is characterized in that described sound wave afferent pathway forms by selective corrosion monocrystalline substrate and porous monocrystalline silicon trap.
10, a kind of method of making the Electret Condencer Microphone of the described single-crystal-silicon micro mechanical processing of claim 1 is characterized in that manufacturing step comprises:
Prepare a monocrystalline substrate;
By anodic oxidation, at inner 200 to 2000 microns of some lateral lengths, first dark 10 to the 20 microns porous monocrystalline silicon trap of forming of monocrystalline substrate;
On the monocrystalline substrate surface, be included in some first porous monocrystalline silicon trap surfaces, the first epitaxy single-crystal silicon layer that grow thick is 3 to 5 microns;
Form 200 to 2000 microns of some lateral lengths by ion injection and high annealing in the first epitaxy single-crystal silicon layer, dark 2.5 to 4.5 microns, mean impurity concentration is 10
18To 10
19/ cm
3Doped region, and make each doped region be in one first porous monocrystalline silicon trap directly over;
By anodic oxidation some doped regions are transformed into some second porous monocrystalline silicon traps;
Form 20 to 100 microns of some width on the first epitaxy single-crystal silicon layer, the complex media bar of thick 2000 to 3000 dusts makes each complex media bar around one second porous monocrystalline silicon trap;
In the first epitaxy single-crystal silicon surface, be included in all second porous monocrystalline silicon trap surfaces, the second epitaxy single-crystal silicon layer that grow thick is 10 to 20 microns, and meanwhile cross the monocrystalline silicon layer of prosperous growth and at centre surface deposition polysilicon layer at plurality of compound medium strip edge superficial growth epitaxial lateral;
Form 20 to 100 microns of some lateral lengths, the upright opening group that Center Gap is 20 to 200 microns, pass the whole second epitaxy single-crystal silicon layer, each upright opening group be in one second porous monocrystalline silicon trap directly over, form some wide 20 to 40 microns irrigation canals and ditches simultaneously, with epitaxy single-crystal silicon layer and the polysilicon layer on the complex media bar, and second the second epitaxy single-crystal silicon layer and the second epitaxial monocrystalline silicon layer region at other position on the porous monocrystalline silicon trap separated, and be partitioned into some the second epitaxial monocrystalline silicon layer regions that are communicated with the first epitaxy single-crystal silicon layers;
Form the number of metal electrode pair, connect the second epitaxial monocrystalline silicon layer region and the first epitaxial monocrystalline silicon layer region that is located in its underpart of perforate respectively;
The second porous monocrystalline silicon trap is removed in selective corrosion, and forming hollow interlayer, and the second epitaxial monocrystalline silicon layer region that it is depended on is unsettled, and becomes thick 10 to 20 microns stiffener plate;
Carry out selective corrosion from the back side of monocrystalline substrate,, each passage is aimed at one first porous monocrystalline silicon trap to form the main part of some sound wave afferent pathways; And
The first porous monocrystalline silicon trap is removed in selective corrosion, finally finishes the formation of sound wave afferent pathway, and makes the first epitaxial monocrystalline silicon layer region that depends on thereon unsettled, and becomes thick 0.5 to 1.5 micron flexible flat.
11, according to the described a kind of method of making the Electret Condencer Microphone of single-crystal-silicon micro mechanical processing of claim 10, it is characterized in that the concrete arrangement that described selective corrosion formation sound wave afferent pathway is carried out in two steps is: the first step adopts deep trouth reactive ion etching technology erosion removal monocrystalline substrate, and terminates in automatically on the interface of the first porous monocrystalline silicon trap; Second step was used volume ratio 49%HF: 30%H
2O
2The first porous monocrystalline silicon trap is removed in the solution selective corrosion that is 1: 5.
12, according to the described a kind of method of making the Electret Condencer Microphone of single-crystal-silicon micro mechanical processing of claim 10, it is characterized in that it is that the concrete arrangement that carries out in two steps of branch is that described selective corrosion forms the sound wave afferent pathway: the first step forms groove with the KOH solution corrosion earlier, make the surplus monocrystalline silicon layer that 10 to 20 micron thickness are arranged in its bottom, use volume ratio 49%HF: HNO then
3: CH
3COOH to 8 solution corrosion removes the bottom of the first porous monocrystalline silicon trap of remaining monocrystalline silicon layer and 3 to 5 micron thickness at 1: 3: 5; Second step was used volume ratio 49%HF: 30%H
2O
2The remaining thick-layer of the first porous monocrystalline silicon trap is removed in the solution selective corrosion that is 1: 5.
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| CN101489170B (en) * | 2009-02-20 | 2012-08-22 | 浙江工业大学 | Self-detecting silicon micromechanical microphone and production method thereof |
| CN101867860B (en) * | 2010-06-11 | 2012-12-12 | 中国科学院声学研究所 | Condenser microphone having split electrodes |
| CN102815661A (en) * | 2011-06-07 | 2012-12-12 | 无锡华润华晶微电子有限公司 | Preparation method of silicon film |
| US9102519B2 (en) * | 2013-03-14 | 2015-08-11 | Infineon Technologies Ag | Semiconductor devices and methods of forming thereof |
| CN106973351B (en) * | 2015-11-26 | 2019-11-15 | 李美燕 | Micro feedback cavity sensor and manufacturing method thereof |
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| 多孔硅在电容式微传声器制备中的应用研究. 宁瑾等.微细加工技术，第2003年第1期. 2003 |
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