CN1140841C - Mechanically modulated WDM transmitting and receiving module - Google Patents
Mechanically modulated WDM transmitting and receiving module Download PDFInfo
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- CN1140841C CN1140841C CNB001077414A CN00107741A CN1140841C CN 1140841 C CN1140841 C CN 1140841C CN B001077414 A CNB001077414 A CN B001077414A CN 00107741 A CN00107741 A CN 00107741A CN 1140841 C CN1140841 C CN 1140841C
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Abstract
The present invention relates to a technique for manufacturing a Fabry-Perot cavity optical mechanical modulator and a wavelength division multiplex transmitting and receiving module composed of the Fabry-Perot cavity optical mechanical modulator. A Fabry-Perot cavity is formed by etching a polysilicon three-laminated structure. A flexible film of the modulator is formed by polysilicon at the upper layer, the corrosion of the polysilicon at the middle layer is removed after the polysilicon at the middle layer is converted into porous polysilicon, and accordingly, the polysilicon at the upper layer is suspended. The suspended polysilicon at the upper layer is finally released by the corrosion of reactive ions. Conical optical fiber insertion holes are integrated in a wafer with the polysilicon laminated structure. The insertion holes are formed by a porous monocrystal silicon technique, and optical fibers automatically aligns to a photoelectric detector placed on the cavity once being inserted.
Description
The invention relates to wavelength-division multiplex (WDM) and transmit and receive module (module), particularly transmit and receive module as the wavelength-division multiplex of light signal transmitter about the opto-mechanical modulator of micromachined (micromachined).
Optical fiber communication, particularly Fiber to the home and optical fiber has stimulated the wavelength-division multiplex of low-cost and high-performance to transmit and receive the demand of module to desk.Developed now and two kinds of main wavelength-division multiplex and transmit and receive module.A kind of module needs a semiconductor laser that is installed on the user place, is used for sending light signal for the user.The modulation rate of semiconductor laser can be up to several Gbit/s, but owing to cost an arm and a leg, and to responsive to temperature, factor such as power consumption is big had both been raised the price of whole module, also had influence on the stable performance of module.The closed circuit framework that returns of another kind of employing, whole module only needs a semiconductor laser that is installed in central office, and at user side, the opto-mechanical modulator of a micromachined replaces semiconductor laser, undertakes the function that sends user's light signal.In this module, the data that central office sends are produced by the semiconductor laser of central office, and the data that the user sends are produced by user's the opto-mechanical modulators modulate light beam from central office.
For many practical applications, the bit rate of user profile is far below the bit rate of central office information, and perhaps several Mbit/s just can satisfy the requirement of user profile.The information of this low bit rate just is being fit to produce with the opto-mechanical modulator of micromachined.The opto-mechanical modulator of micromachined has low cost of manufacture, and it is low to insert loss, contrast height and to advantages such as polarity are insensitive, so the opto-mechanical modulator of micromachined to replace semiconductor laser be a kind of economical and practical, the replacement scheme of being convenient to promote.
To the research and development of opto-mechanical modulator, can trace back to before decades, the working method that is early stage opto-mechanical modulator mostly is phase-shift type or scanning mirror greatly, and its modulation rate is too low, does not satisfy the needs of optical fiber communication.In recent years, developed micromachined (micromachining) technology, and produced panoramic microelectromechanical-systems and low-light electric system with this technology based on integrated circuit technique.Relatively successful low-light electric system is Fabry-Perot (Fabry-Perot) chamber opto-mechanical modulator.Fabry-Perot-type cavity is made of two parallel reflectings surface, and the distance between two reflectings surface has only the several times of 1/4th optical wavelength.For meticulous Fabry-Perot-type cavity like this, as adopt traditional Machining Technology, not only manufacture process is extremely complicated, and machining precision also is difficult to guarantee.Adopt micromachining technology, whole manufacturing process becomes implements several roads simple semiconductor worker State-of, and requirement on machining accuracy is all within conventional semiconductor machining scope.
Figure 1A and Figure 1B show opto-mechanical modulator (the James A.Walker of a kind of micromachined of bibliographical information, Keith W.Goossen, and Susanne C.Arney, " Fabrication of a Mechanical Antireflection Switch for Fiber-to-the-Home System; " Journal of Microelectromeehanical Systems, Vol.5 (1), pp.45-51, March 1996).The Fabry-Perot-type cavity of this modulator is by substrate 101, clearance 103, and around the aluminium support frame 102 of clearance, and silicon nitride (Si
3N
4) film 104 formations.Si
3N
4Film 104 comprises central authorities dull and stereotyped 106 and brace summer 107 two parts all around, unsettled as a whole being across on the substrate 101.Upper electrode 105 covers brace summers 107 all and the marginal portion of central authorities dull and stereotyped 106, and the core of central flat board 106 still exposes Si
3N
4Film is as optical transmission window 108.For the operation device, signal voltage must be put between upper electrode 105 and the bottom electrode 109, produce electrostatic forcing thus in upper electrode 105, make Si
3N
4Film along with signal voltage to substrate 101 direction bendings.When voltage is zero, Si
3N
4Clearance 103 between film 104 and the substrate 101 is the odd-multiple of λ/4 (wherein λ is the work optical wavelength), and Fabry-Perot-type cavity is to the reflection coefficient maximum of incident beam at this moment; Along with voltage increases, Si
3N
4Film begins to bend towards substrate 101, when making clearance 103 be the even-multiple of λ/4, and the reflection coefficient minimum of Fabry-Perot-type cavity.Adopt this method to change Fabry--the distance between Perot cavity two reflectings surface, can modulate the intensity of folded light beam, make it become the light signal that is loaded with user profile.
Although adopting with aluminium is sacrifice layer and with Si
3N
4Be elastic membrane, more convenient really from making the angle consideration, but bring many rather serious puzzlements.When the thickness of aluminium lamination during near 1 micron, its surface coarse injustice that becomes, and a large amount of hillocks appear thereupon, this makes the Si that is formed on the aluminium lamination
3N
4Film produces highdensity pin hole.Si
3N
4Film also is used as the insulation course of metal line except that as the structured material, and densely covered pin hole and aluminium lamination hillock can cause electric pole short circuit and component failure.In addition, micromachined is used for substrate is carved and excavated, and to form the three-dimensional micro structure, therefore the selectivity of corrosion is the problem of overriding concern.The selectivity of this corrosion is even more important to the forming method Fabry-Perot-type cavity, because the subtle change of the vertical and horizontal size in chamber all can cause the significant difference of its optical property.When doing to form the expendable material of cavity body structure with aluminium, the lateral encroaching of aluminium can not stop voluntarily.The lateral dimension control of cavity not, cavity vibration characteristics just can not repeat, the working voltage of cavity also just is difficult to determine.
The design of another opto-mechanical modulator is (C.Marxer as shown in Figure 2, M.A.Gretillat, V.P.Jaecklin, R.Baettig, O.Anthamatten, P.Vogel, N.F.de Rooij, " Megahertz opto-mechanical modulator; " Sensors andActuators A, Vol.52 (1-3), pp.46-50, March/April 1996).The Fabry-Perot-type cavity of this modulator is by bottom polysilicon catoptron 203, and polysilicon upper reflector 205 and clearance 206 are formed.Cavity is formed on the monocrystalline silicon piece 201.For forming cavity, at first form Si on monocrystalline silicon piece 201 surfaces
3N
4Layer 204 is as anti-reflection film.Then at Si
3N
4Layer 204 surface form bottom polysilicon catoptron 203.Then form phosphorosilicate glass (PSG) layer, as the sacrifice layer (not drawing among the figure) of selective etching.After the PSG layer is processed to island, on the PSG island, form polysilicon layer.Selective etching PSG island promptly forms arch bridge shape polysilicon upper reflector 205.Polysilicon, Si
3N
4, and PSG is formed by low-pressure chemical vapor deposition (LPCVD) technology.The back side of monocrystalline silicon piece 201 is coated with dielectric layer 202, and there is cavity 207 in centre, the back side.Optical fiber 209 is inserted by cavity 207, and the pore hole of fibre core 208 aligned with lower polysilicon catoptrons 203 bottoms enters cavity by its emitted light beams by the pore hole.
Also there are many weak points in this opto-mechanical modulator.1) but desirable Fabry-Perot-type cavity requires the material of unstressed or low tension stress to constitute the catoptron of deformation.The polysilicon layer that forms with the LPCVD technology on monocrystalline silicon piece is not only accomplished unstressed or low tension stress, opposite but have enough big residual compressive stress to exist, cause the loose wrinkle of polysilicon film that discharged by the corrosion sacrifice layer, be difficult to constitute desirable plane mirror.2) uneven as the PSG laminar surface of sacrifice layer, the roughness that causes the polysilicon film surface is up to 140 , and its consequence is the insertion loss that increases modulator.3) because the clearance is too big, cause the device working voltage up to 70V, this is very inconvenient to the application that cooperates microelectronic circuit, particularly microprocessor.4) the formation figure in optic fibre patchhole hole is determined by monocrystalline silicon piece back side dielectric layer litho pattern, back side dielectric layer litho pattern is difficult to and aims at the positive Fabry-Perot-type cavity that forms of monocrystalline silicon piece, this means that the optical fiber of insertion can not be aimed at automatically with Fabry-Perot-type cavity.
Problem or puzzlement that the opto-mechanical modulator of above-mentioned micromachined exists are also on the opto-mechanical modulator that appears at other similar micromachined that all degree is different.Aim of the present invention is exactly that the structure of existing opto-mechanical modulator and manufacture method thereof are carried out key technological transformation, fundamentally eliminate to produce the cause of the problems referred to above or puzzlement, with the opto-mechanical modulator of the micromachined that produces high-performance and low-cost.
It is the opto-mechanical modulator of basic composition with the Fabry-Perot-type cavity that one of purpose of the present invention provides a kind of, and its cavity is processed by the pellicular cascade of homogeneous material, rather than the pellicular cascade that resembles the modulator the preceding by dissimilar materials processes.Adopt the pellicular cascade of homogeneous material, can eliminate the cavity film residual stress that coefficient of thermal expansion mismatch and lattice constant mismatch by different materials cause, to obtain even more ideal plane mirror.
It is the opto-mechanical modulator of basic composition with the Fabry-Perot-type cavity that two of purpose of the present invention provides a kind of, but the formation of its cavity deformation film is carried out in two steps, the first step is removed the partial sacrifice layer by wet etching, remove residual sacrifice layer by dry etching for second one, rather than resemble the preceding and only to adopt one step of wet etching to form the modulator.Dry etching can be eliminated solution surface tension effect intrinsic in the wet etching, thereby but eliminates the phenomenon that the deformation film that corrodes release is pulled to substrate and pastes with the substrate generation.
It is the opto-mechanical modulator of basic composition with the Fabry-Perot-type cavity that three of purpose of the present invention provides a kind of, the airspace of its cavity can reduce to the minimum value of Design Theory, rather than as modulator the preceding, owing to the restriction that is subjected to manufacturing technology has to get bigger value.Smaller airspace can reduce the required voltage of modulator operation, provides convenience for cooperating microelectronic circuit to use.
It is the opto-mechanical modulator of basic composition with the Fabry-Perot-type cavity that four of purpose of the present invention provides a kind of, but the deformation film of its cavity is made of the film that is formed on the relatively thinner sacrifice layer.Relatively Bao sacrifice layer has the surface of smoother, but thereby the deformation film surface of smoother is also arranged, thereby reduce the insertion loss of modulator.
It is that the opto-mechanical modulator of basic composition has the optic fibre patchhole hole of aiming at cavity with the Fabry-Perot-type cavity that five of purpose of the present invention provides a kind of, cavity and optic fibre patchhole hole are formed at same substrate, one common peripheral makes optical fiber can aim at cavity automatically once inserting around same central axis.
It is the opto-mechanical modulator of basic composition with the Fabry-Perot-type cavity that six of purpose of the present invention provides a kind of, and its cavity and its substrate surface are in same plane, is not to resemble the preceding to protrude from substrate surface the modulator.The complanation of cavity not only is convenient to directly adopt ripe semiconductor planar technology to make, and helps increasing the physical strength of modulator, reduces the loss in the manufacture process, improves the yield rate of product.
To achieve these goals and other purpose, the present invention proposes a kind of is that the wavelength-division multiplex of transmitter sends and the manufacture method of receiver module with the opto-mechanical modulator.This module as shown in Figure 3, its Fabry-Perot-type cavity is by top polysilicon catoptron and flexible polycrystalline beam 304, bottom polysilicon catoptron 302, and the clearance between the two polysilicon catoptrons 306 is formed.The front center of top polysilicon catoptron is coated with top anti-reflective film 305.Metal electrode 310 covers polysilicon beam and most of polysilicon catoptron area, and top anti-reflective film 305 is exposed in the centre of polysilicon catoptron down.The back side of bottom polysilicon catoptron 302 is coated with bottom anti-reflective film 303.Metal electrically contacts 308 and is connected with diffusion layer 301 in the monocrystalline silicon piece, because the superficial layer of diffusion layer 301 is the high-dopant concentration district, impressed voltage directly can be passed to the bottom of polysilicon catoptron 302 by this high-dopant concentration district. Metal lead wire 313 and 314 leads to external circuit, introduces modulation signal for cavity, cavity top polysilicon catoptron and flexible polycrystalline beam 304 can be bent, with the distance between change and the bottom polysilicon catoptron 302 with modulation signal.
The Fabry-Perot-type cavity of this module is processed by polysilicon three lamination structures 307, and this rhythmo structure is formed on the diffusion layer 301 of monocrystalline silicon piece.The top polysilicon catoptron of cavity and flexible polycrystalline beam 304 were the part of its top polycrystal layer originally, and after polysilicon layer under it was removed in selective corrosion, this part polysilicon layer just rises to the sky became rich flexible structure.Middle polysilicon layer has three effects: the sacrifice layer that 1) is used to form top polysilicon catoptron and flexible polycrystalline beam 304; 2) be used to form the building materials of top polysilicon catoptron and flexible polycrystalline beam 304 support frames; 3) as isolating top polysilicon catoptron and flexible polycrystalline beam 304 semi-insulating layer with diffusion layer 301.The bottom polycrystal layer is clipped between top polycrystal layer and the following diffusion layer 301, play the cushion effect, to reduce the influence of two kinds of material thermal expansion coefficient mismatches and lattice mismatch, reduce the unrelieved stress in top polysilicon catoptron and the flexible polycrystalline beam 304 to top polysilicon catoptron and flexible polycrystalline beam 304.
Photodiode 316 is installed on the Fabry-Perot-type cavity, its sensitive surface 317 down and aim at top anti-reflective film 305, it protrudes welding block 318 and connects monocrystalline silicon pieces, and 316 on photodiode is supported and positioning action.The diffusion layer 301 of monocrystalline silicon piece is around a cone shape hole 315.Monocrystalline silicon piece bonds itself and glass sheet 312 with bonding agent 311 behind thinning back side, makes the cone shape hole 315 of the through-hole alignment monocrystalline silicon piece in the glass sheet.Optical fiber 319 inserts cone shape hole 315, and is fixed in glass sheet 312 with resin 321.The trans D of cone shape hole 315 is adjusted to the trans D of optical fiber and matches, the fibre core 320 that inserts optical fiber 319 need not carry out the central axis that the position adjustment just can be aimed at cavity automatically, can accurately shine on the light sensitive volume 317 of photodiode 316 after the light beam that fibre core is sent sees through cavity.
The porous polycrystalline silicon micromachining technology that forms and corrode porous polycrystalline silicon based on selectivity is adopted in the top polysilicon catoptron of Fabry-Perot-type cavity and the release of flexible polycrystalline beam 304.Dispose procedure mainly comprises: form polysilicon three lamination structures on monocrystalline silicon piece, and polysilicon three lamination structures are carried out the part mix, make the central region in middle level and the middle part regional area of lower floor become heavily doped region, and still center on around these zones by unadulterated high resistance polysilicon.The upper strata polycrystal layer is opened some openings, with the heavily doped region in exposed portions serve middle level.Insert hydrofluorite (HF) solution and carry out anodic oxidation, heavily doped polysilicon selective is transformed into porous polycrystalline silicon, use the weak mordant of silicon then, potassium hydroxide solution as dilution, the porous polycrystalline silicon that selective corrosion forms, thereby discharge the former polysilicon layer that is on the heavily doped region in top, make it become the film of easy deformation.
The porous monocrystalline silicon micromachining technique that forms and corrode porous monocrystalline silicon based on selectivity is adopted in the formation of cone shape hole in the monocrystalline silicon piece.Cone shape hole forming process mainly is the n type diffusion layer that forms toroidal in the lightly doped monocrystalline silicon piece of p type, and the p shape district that annulus centers on is the big circular cone in little bottom, top.Form polysilicon three lamination structures at monocrystalline silicon sheet surface, make rhythmo structure and cone shape p type district around same central axis.After the heavily doped polysilicon of rhythmo structure is transformed into porous polycrystalline silicon, proceed anodic oxidation reactions, make the cone shape p type monocrystalline silicon in the monocrystalline silicon piece be transformed into porous monocrystalline silicon, with the porous monocrystalline silicon erosion removal that forms, just formed the big cone shape hole in little bottom, top then.
The cone shape hole that forms behind the corrosion porous monocrystalline silicon has smooth sidewall, and the diameter of its xsect from top to bottom changes continuously.The circle diameter of control n type diffusion layer makes it be slightly smaller than the diameter that inserts optical fiber, and then must there be a place middle part of cone shape hole, and its cross-sectional diameter cooperates with fibre diameter.Need not also needn't carry out loaded down with trivial details manually-operated by exact instrument, optical fiber must overlap with the central axis of cavity automatically once insertion.
Paste for avoiding cavity top polysilicon catoptron and flexible polycrystalline beam 304 and following polysilicon film 302, behind the corrosion porous polycrystalline silicon, the polysilicon beam part of top polysilicon catoptron and flexible polycrystalline beam 304 is still supported by the undoped polycrystalline silicon wall at its edge, and the plate part of polysilicon film is still supported by the undoped polycrystalline silicon post that scatters wherein.At this moment the polysilicon film that is discharged still has enough rigidity intensity, stops the effect of etchant solution capillary force, and unlikely by stretch bending to separated polysilicon layer contact.These undoped polycrystalline silicon walls and undoped polycrystalline silicon post are removed by dry etching at last.There is not the effect of etchant solution capillary force in dry etching, thereby the problem of polysilicon film that can not occur discharging and the stickup of bottom polysilicon layer.
Undoped polycrystalline silicon wall and undoped polycrystalline silicon post are set among the heavily doped polysilicon, when heavily doped polysilicon is on every side become porous polycrystalline silicon by anodic oxidation, because the semi-insulating characteristic of undoped polycrystalline silicon, can stop anode current therefrom to pass through, thereby can not become porous polycrystalline silicon by anodic oxidation.The etchant solution of porous polycrystalline silicon corrosion usefulness is the potassium hydroxide solution corrosion of dilution, corrosion is at room temperature carried out, with this understanding, corrosion to polysilicon is insignificant, thereby in the corrosion process of subsequently porous polycrystalline silicon, undoped polycrystalline silicon wall and undoped polycrystalline silicon post are not influenced by any corrosion.
For adopting dry etching choice of technology removal undoped polycrystalline silicon wall and undoped polycrystalline silicon post; diaphragm on polysilicon wall and the polysilicon pillar must have different protection features with the diaphragm on the polysilicon film; they all have the ability of anti-HF solution corrosion; thereby prevent that its surface is damaged in anode oxidation process; but in the dry etching process; diaphragm on the polysilicon film still has erosion-resisting effect, and the diaphragm on polysilicon wall and the polysilicon pillar no longer has erosion-resisting effect.For satisfying these requirements, the diaphragm on the polysilicon film is selected Si for use
3N
4And silicon dioxide (SiO
2) composite bed, and the diaphragm on polysilicon wall and the polysilicon pillar is selected Si for use
3N
4Individual layer.The dry etching agent of selecting for use is to Si
3N
4Must be higher than with the corrosion rate of polysilicon SiO
2Corrosion rate, and metal is not corroded basically Cl
2+ He etchant gas series just has this specific character.
The cross sectional representation of the opto-mechanical modulator of a kind of micromachined that technology provided before Fig. 1 was illustrated in.
The cross sectional representation of the opto-mechanical modulator of the another kind of micromachined that technology provided before Fig. 2 was illustrated in.
Fig. 3 shows that wavelength-division multiplex that the opto-mechanical modulator with micromachined provided by the invention is a transmitter sends and the cross sectional representation of receiver module.
Fig. 4 to Figure 14 show that wavelength-division multiplex that the opto-mechanical modulator with micromachined provided by the invention is a transmitter sends and receiver module at it each main manufacturing step finish the rear section and excise skeleton view.
The pattern exhibiting that cooperates Fig. 4 to Figure 14, the wavelength-division multiplex that to introduce the opto-mechanical modulator with micromachined provided by the invention in detail be transmitter send and the manufacture process of receiver module.
With reference to Fig. 4, lightly doped p type monocrystalline silicon piece 401 is as backing material, the SiO of about 1 micron thickness
2Formed thereon surface of layer, the technology of employing is the thermal oxide of high temperature wet oxygen.By photoetching and corrosion, with SiO
2Layer is processed into the masking graphics that includes opening.Carry out the elevated temperature heat diffusion then, in monocrystalline silicon piece 401, form about 20 microns dark n type diffusion layers 402.Diffusion layer 402 is toroidal, about 110 microns of internal radius at substrate surface.The p type district that diffusion layer 402 centers on is a cone shape, about 110 microns of its top diameter, about 134 microns of base diameter.
With reference to Fig. 5, form polysilicon layer 404 on the surface of monocrystalline silicon piece 401, the technology of employing is LPCVD, and depositing temperature is 620 ℃, and source of the gas is SiH
4, reaction pressure is 220mTorr.The thickness of this polysilicon layer is m λ/4, and wherein m is an odd number, and m is 1 under the typical situation.Polysilicon layer 404 does not have a mind to mix, and its resistivity is higher than 10
6Ω cm.Low temperature silicon dioxide (LTO) layer of about 1 micron thickness is formed on the polysilicon layer 404, and the technology of employing is LPCVD, and depositing temperature is 560 ℃, and source of the gas is O
2And SiH
4, reaction pressure is 150mTorr.Adopt photoetching and corrosion technology the LTO layer to be processed into the masking graphics that comprises opening.Carry out phosphonium ion then and inject, implantation dosage is 1 * 10
15/ cm
2, the injection energy is 60kev.Then carry out thermal annealing, annealing temperature is 1100 ℃, and annealing time is 30min.Form four heavily doped regions 405 thus, round the central axis symmetrical distribution of cone shape p type monocrystalline silicon region, and each heavily doped region bottom major part is located in the cone shape p type monocrystalline silicon region.
With reference to Fig. 6, in the hydrofluoric acid solution (BHF) of buffering, behind the erosion removal LTO layer, adopt LPCVD technology same as described above on polysilicon layer 404, to form another polysilicon layer 406.The thickness of this polysilicon layer is m λ/4, and m is 3 in typical case.Form another LTO layer with LPCVD technology same as described above, and be processed into the masking graphics that includes opening.Inject and the high-temperature thermal annealing technology with phosphonium ion same as described above, in polysilicon layer 406, form foursquare heavily doped region 407.The many unadulterated little square block of heavily doped region 407 intermediate distribution district 408 and little rectangular block district 409.The base section of heavily doped region 407 is located in the heavily doped multi-crystal silicon area 405, and the base section in unadulterated little square block district 408 and little rectangular block district 409 is located in the unadulterated multi-crystal silicon area.
With reference to Fig. 7, erode the LTO layer after, on second polysilicon layer, 406 surfaces, adopt LPCVD technology same as described above to form the 3rd polysilicon layer 410.The thickness of this polysilicon layer is m λ/4, and m is 1 in typical case.And then be processed to form contact hole 413 with photoetching and corrosion technology.Contact hole 413 must pass through, in, following three layers of polysilicon layer 404,406 and 410 are deep into the surperficial high-dopant concentration district of n type diffusion layer 402 always.Reactive ion etching (RIE) technology is adopted in the corrosion of polysilicon, and the etchant gas prescription is Cl
2+ He=180: 400sccm, RF power are 275W, and reaction pressure is 300mToor, and underlayer temperature is 40 ℃.Then, with LPCVD technology same as described above, form the LTO layer 411 of thick λ/4 on 410 layers surface.With photoetching and corrosion technology LTO layer 411 is processed, make and form the opening 414 that exposes bottom polysilicon layer 410, the central part of opening 414 is reserved the foursquare LTO table top of 20 * 20 μ m as anti-reflective film 412, and the center of this anti-reflective film is on the central axis of cone shape p type monocrystalline silicon region.In this photoetching and corrosion process, the LTO layer of contact hole 413 bottoms is erosion removal together, electrically contacts so that make metal subsequently.
With reference to Fig. 8,, form the thick low stress Si of 1000 with the LPCVD technology on the surface of monocrystalline silicon piece 401
3N
4Layer 415, the source of the gas of employing is SiH
2Cl
2(DCS)/NH
3=0.176, depositing temperature is 790 ℃, and reaction pressure is 150mToor.With photoetching and corrosion technology to low stress Si
3N
4 Layer 415 is processed to form Si
3N
4Figure 416.Si
3N
4Figure 416 comprises the square platform of middle part 30 * 30 μ m, and this platform covers the anti-reflective film 412 under it fully.Si
3N
4Figure 416 also comprises the long pawl of " Z " shape of four wide 10 μ m of long 40 μ m, and this long pawl stretches out from the middle part, edge of square platform, links to each other with the framework of outer rim, top polysilicon layer 410 exposed in the frame is divided into the opening 414 of four homalographics.When photoetching corrosion forms opening 414, the Si of palpus erosion removal contact hole 413 bottoms
3N
4Layer.
With reference to Fig. 9, on the surface of monocrystalline silicon piece 401, the deposited by electron beam evaporation technology forms thick Cr layer of 200 and the thick Au layer of 200 successively, forms the Au/Cr composite bed thus, and wherein Cr increases the Au layer to Si as bonding agent
3N
4The viscosity of layer.With photoetching and corrosion technology the Au/Cr composite bed is processed to form composite bed figure 419.This composite bed figure covers most of square Si
3N
4Platform, but must vacate four little square block of part and the edge zone 418 that is on the anti-reflective film 412.Composite bed figure 419 also covers most of " Z " shape Si
3N
4Long pawl, but vacate the little rectangular block zone 417 at edge.Composite bed is processed the metal that also forms simultaneously in the contact hole electrically contact 420 and be arranged in the metal pressure- welding block 421 and 422 of composite bed figure 419 both sides.Metal pressure-welding block 421 electrically contacts 420 with metal and is connected, and metal pressure-welding block 422 is connected with composite bed figure 419.Metal pressure- welding block 421 and 422 must further be thickeied about about 20 microns with electroplating technology.Remove not by Si with photoetching and corrosion technology then
3N
4Cover the top polysilicon layer, form the opening 423 that exposes the middle part heavily doped region.
Next be porous polycrystalline silicon and the porous monocrystalline silicon that forms as the micromachined sacrifice layer.Porous polycrystalline silicon and porous monocrystalline silicon can both be generated by anodic oxidation in concentration ratio higher H F solution, but the property according to qualifications of its generation is relevant with the doping type and the doping content of material.No matter be polysilicon and monocrystalline silicon, general rule is, heavy doping p+ type silicon generates porous silicon than light dope p type and the preferential anodic oxidation of light dope n type silicon, and heavy doping n+ type silicon is than heavy doping p+ type, and the preferential anodic oxidation of light dope p type silicon and light dope n type silicon generates porous silicon.By the control anodic oxidation voltage, can on light dope n type silicon substrate, preferentially form porous silicon in other words, also can on light dope p type silicon substrate, preferentially form porous silicon at heavy doping p+ and heavy doping n+ type silicon area at heavy doping n+ type silicon area.
The anodizing tank that uses is two chambers teflon grooves.Treat the middle part of anodised monocrystalline silicon piece insertion groove chamber, the groove chamber is separated into two sulculuses of mutually isolating, a tabular platinum electrode is placed in the opposite end of each sulculus, is connected with external dc power, and DC voltage is put on HF solution in the groove.HF solution has two kinds of effects, and the one, play anodizing in the front of monocrystalline silicon piece, the 2nd, play a part to electrically contact at the back side of monocrystalline silicon piece.HF solution is driven by chemical pumping it is constantly circulated in groove, be bonded at monocrystalline silicon sheet surface with expeling, by the bubble of anodic oxidation reactions generation, and provide beating action that solution concentration is evenly distributed, avoid significantly reducing because of reaction consumes in conversion zone HF concentration.
HF is a highly corrosive agents, treats that anodised monocrystalline silicon piece 401 surfaces will be protected in order to avoid damaged.Protective seam will have the ability of enough anti-HF corrosion.The material of anti-HF corrosion is a lot, the low stress Si that has LPCVD to form commonly used
3N
4, amorphous Si C and amorphous silicon (Si) that PECVD forms, and Au and Pt etc.The low stress Si that selects for use LPCVD to form above
3N
4, the energy force rate of its anti-HF corrosion meets the Si of stoicheiometry
3N
4By force.
The prescription of the HF solution of selecting for use is HF (49%): C
2H
5OH (96vol%)=1: 1.Add C in the solution
2H
5OH (absolute ethyl alcohol) is in order to strengthen the penetrating power in the micropore hole of HF solution, and the hydrogen gas bubbles that is attached to monocrystalline silicon piece 401 surfaces can be removed as soon as possible.During anodic oxidation, anodic current density remains on about 50mA/cm
2About, solution temperature maintains about room temperature.
With reference to Figure 10, by anodic oxidation, earlier with larger area heavily doped region 407 in the middle polysilicon layer, heavily doped region 405 than small size in the polysilicon layer of bottom is transformed into porous polycrystalline silicon 424, and the cone shape p type district 403 that n type diffusion layer 402 in the monocrystalline silicon piece 401 is surrounded is transformed into porous monocrystalline porous silicon 425 then.The degree of depth of the porous monocrystalline porous silicon layer 425 that forms generally can be controlled in about 60-80 μ m along with anodizing time increases, to meet the conventional thickness that 401 of attenuate monocrystalline silicon pieces subsequently can reach.
With reference to Figure 11, monocrystalline silicon piece 401 is bonded on the glass sheet (do not drawn among the figure), make its face down, the back side up, bonding agent can be used photoresist, such as the negative photoresist of KPR series, about 120 ℃ of the pre-bake temperature of this photoresist.Use attenuate machine attenuate then, to expose the porous monocrystalline silicon area 425 of formation.The hard sheet 427 that again another is carved with through hole adheres on the monocrystalline silicon piece 401, and the through hole 428 of hard sheet is aimed at the appearing of porous monocrystalline silicon 425 of monocrystalline silicon piece 401, bonding agent low temperature curing resin 426.Hard sheet material is a metal, plastic cement, and glass etc. must have enough physical strengths, and process accurate through hole easily.Must be lower than warm the giving up 120 ℃ of preceding baking of negative photoresist as the resin solidification temperature of bonding agent.With the negative photoresist of the molten removal of developer solution of negative photoresist, remove the glass sheet in monocrystalline silicon piece 401 fronts subsequently, to expose its positive polysilicon graphics that forms.
With reference to Figure 12,5%KOH solution corrosion porous porous silicon 424 and porous monocrystalline silicon 425 with dilution form top polysilicon film 430 thus, four polysilicon beams 431 linking to each other of film therewith, the clearance 432 between bottom polysilicon film 433, two polysilicon films.At this moment, top polysilicon film 430 is supported by four undoped polycrystalline silicon posts 435, and every polysilicon beam 431 is supported by two undoped polycrystalline silicon walls 434.Must notice that the bottom of undoped polycrystalline silicon wall 434 and undoped polycrystalline silicon post 435 is the not doped region of polysilicon layer 404, the top is coated with Si
3N
4Film.Last on the surface of bottom polysilicon film 433, the deposited by electron beam evaporation technology forms the thick LTO layer in λ/4, as anti-reflective film 429.
With reference to Figure 13, do not need to form again any new masking film on the surface of monocrystalline silicon piece 401, directly use RIE technology erosion removal undoped polycrystalline silicon wall 434 and undoped polycrystalline silicon post 435.Etchant gas is Cl
2+ He=180: 400sccm, RF power are 275W, and reaction pressure is 300mT, and base-plate temp is 40 ℃.The corrosion rate of Chan Shenging is 5700 /min to polysilicon, to low stress Si with this understanding
3N
4Being 530 /min, is 60 /min to LTO, and Au/Cr is not corroded basically.Hence one can see that, and Au/Cr and LTO are good corrosion-resistant materials.RIE corrodes Si
3N
4The situation of/LTO is first two-forty corrosion Si
3N
4Layer, low speed corrosion LTO layer by the control etching time, stops corrosion in position then, to preserve anti-reflective film 411 enough thickness is arranged.RIE corrodes Si
3N
4The situation of/polysilicon is high speed erosion removal Si
3N
4Behind the layer, that expose is polysilicon rather than LTO, and mordant still has very high corrosion rate to polysilicon, thereby can continue to corrode, and middle part polysilicon layer 406 is eroded and exposes bottom polysilicon layer 404 very soon.After RIE corrosion, polysilicon film 430 separates with the polysilicon layer 404 of bottom fully with polysilicon beam 431, and polysilicon layer 406 therebetween no matter be heavily doped region or doped region not, all be corroded and remove totally.Must notice that the heavily doped polysilicon of polysilicon layer 406 partly is to be fallen by the KOH solution corrosion that dilutes after forming porous polycrystalline silicon, the undoped polycrystalline silicon part is directly eroded by RIE.
As everyone knows, there is the effect of capillary force in solution corrosion, can cause the microstructure adhesion.The product of solution corrosion also can remain in microstructure formation place, becomes another factor that causes the microstructure adhesion.The mordant and the reaction product of RIE corrosion all are gas, and reaction chamber is in the infrabar state, and reaction product is difficult for stopping in microstructure formation place.The problem that therefore above-mentioned solution corrosion exists can not occur in dry etching.
With reference to Figure 14, above monocrystalline silicon piece 401, the soldering projection 441 of photodiode is docked one by one with soldering projection 421 on the monocrystalline silicon piece 401 photodiode 439 device, guarantee that the light sensitive volume 440 of photodiode 439 aims at anti-reflective film 412.Then optical fiber 437 is inserted the optic fibre patchhole hole of the cone shape of monocrystalline silicon piece 401 by the via holes of glass sheet 427.The diameter of single-mode fiber is 125 μ m, and just in time between the trans D of top and the bottom, optic fibre patchhole hole, thereby the insertion end of optical fiber can stop on the inwall that inserts the hole ramped shaped, keeps with the lower surface of bottom polysilicon film 433 distance of determining being arranged.As long as optical fiber 437 is vertical insertions, its fibre core will be aimed at the central axis that inserts hole automatically, also promptly aim at by top polysilicon film 430, top polysilicon beam 431, bottom polysilicon film 433, the central axis of the Fabry-Perot-type cavity that constitutes with intermediate air gap 432, and the light sensitive volume 440 of the photodiode 439 of cavity top.
That introduces above is the opto-mechanical modulator of the micro mechanism processing that proposes of the present invention and is the optimum implementation that the wavelength-division multiplex of transmitter sent and received the film piece with it.The those of skill in the art in present technique field are according to above-mentioned introduction, are easy to manufacture method that the present invention is provided and some aspect of manufacturing process and make amendment, and increase and delete, but can not leave base region that limits of the present invention and essence spirit in essence.
Claims (10)
1. a manufacturing machine modulation system transmits and receives the method for module, it is characterized by manufacturing step and comprises: the p type district that (A) forms the cone shape that is centered on by n type diffusion layer in lightly doped p type monocrystalline substrate;
(B) on monocrystalline substrate, form local polysilicon three lamination structures of mixing, make its middle level include a heavily doped region that area is bigger, wherein scatter the less not doped region of some areas, the less heavily doped region of some areas is contained in lower floor, middle level heavily doped region and lower floor's heavily doped region have the part area overlapping, the p type district of lower floor's heavily doped region and monocrystalline substrate female cone shape has the part area overlapping, is partitioned into polysilicon film and the polysilicon beam that the Shang Weicong bottom discharges from upper strata undoped polycrystalline silicon layer;
(C) in hydrofluoric acid solution, carry out anodic oxidation, heavily doped polysilicon is transformed into porous polycrystalline silicon, and keep undoped polycrystalline silicon, comprise interspersing among small size in the heavily doped region the polysilicon in the doped region being not constant;
(D) in hydrofluoric acid solution, carry out anodic oxidation, the p type monocrystalline silicon of cone shape is transformed into porous monocrystalline silicon;
(E) from the thinning back side of monocrystalline substrate to expose the porous monocrystalline silicon of formation;
(F) will there be the supporting pieces of through hole and monocrystalline substrate to bond, make its through hole and the porous monocrystalline silicon pattern alignment that exposes;
(G) corrosion porous polycrystalline silicon and porous monocrystalline silicon in the alkali solution of dilution, part discharges polysilicon film and polysilicon beam, and forms the optic fibre patchhole hole of cone shape;
(H) remove the small size undoped polycrystalline silicon that interspersed among originally in the polysilicon heavily doped region of middle level with dry etching, with whole release polysilicon films and polysilicon beam.
2. a kind of manufacturing machine modulation system according to claim 1 transmits and receives the method for module, it is characterized by manufacturing step and also comprises the anodic oxidation protective seam that forms hydrofluoric acid corrosion resistance.
3. a kind of manufacturing machine modulation system according to claim 2 transmits and receives the method for module, it is characterized by manufacturing step and also comprises described anodic oxidation protective seam separated into two parts, and the part of protection polysilicon film and polysilicon beam is by deposition Si
3N
4And SiO
2Composite bed forms, and the undoped polycrystalline silicon part that protection is removed by dry etching subsequently is by deposition Si
3N
4Individual layer forms.
4. a kind of manufacturing machine modulation system according to claim 1 transmits and receives the method for module, it is characterized by manufacturing step and also comprises the metal line that forms hydrofluoric acid corrosion resistance.
5. a kind of manufacturing machine modulation system according to claim 4 transmits and receives the method for module, it is characterized by described metal line by being adhesion layer with chromium, is that the composite bed of conductive layer forms with the gold.
6. a kind of manufacturing machine modulation system according to claim 1 transmits and receives the method for module, it is characterized by described dry etching agent to Si
3N
4Be easy to SiO with the corrosion of polysilicon
2Corrosion, and Jin Hege is corroded hardly.
7. a kind of manufacturing machine modulation system according to claim 1 transmits and receives the method for module, and it is characterized by described porose supporting pieces is glass sheet.
8. a kind of manufacturing machine modulation system according to claim 1 transmits and receives the method for module, and it is characterized by described porose supporting pieces is sheet metal.
9. a kind of manufacturing machine modulation system according to claim 1 transmits and receives the method for module, it is characterized by manufacturing step and also comprises photodiode is installed on the monocrystalline substrate, makes its light sensitive area aim at the central axis of polysilicon film.
10. a kind of manufacturing machine modulation system according to claim 1 transmits and receives the method for module, it is characterized by manufacturing step and also comprises the optic fibre patchhole hole of optical fiber being inserted cone shape.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CNB001077414A CN1140841C (en) | 2000-05-25 | 2000-05-25 | Mechanically modulated WDM transmitting and receiving module |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CNB001077414A CN1140841C (en) | 2000-05-25 | 2000-05-25 | Mechanically modulated WDM transmitting and receiving module |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN1326104A CN1326104A (en) | 2001-12-12 |
| CN1140841C true CN1140841C (en) | 2004-03-03 |
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|---|---|---|---|
| CNB001077414A Expired - Fee Related CN1140841C (en) | 2000-05-25 | 2000-05-25 | Mechanically modulated WDM transmitting and receiving module |
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| CN (1) | CN1140841C (en) |
Families Citing this family (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102097490A (en) | 2009-12-15 | 2011-06-15 | 中芯国际集成电路制造(上海)有限公司 | Method for manufacturing double-bit flash memory |
| CN102097385B (en) * | 2009-12-15 | 2014-05-07 | 中芯国际集成电路制造(上海)有限公司 | Method for manufacturing two-bit flash memory |
| CN103183307B (en) * | 2011-12-28 | 2016-04-20 | 中国科学院微电子研究所 | Tensile stress LPCVD SiO2Method for producing film |
| CN105271102B (en) * | 2014-06-13 | 2017-02-01 | 北京卓锐微技术有限公司 | Micro mechanical structure based on doping polysilicon and preparation method thereof |
| CN109870255B (en) * | 2017-12-05 | 2023-09-12 | 北京佰为深科技发展有限公司 | Fabry-Perot sensor and manufacturing method thereof |
| CN110527936B (en) * | 2019-09-24 | 2020-11-10 | 北京理工大学 | Array type high-energy elastic wave reduction and homogenization component residual stress device and method |
| CN114823939B (en) * | 2022-04-28 | 2024-01-09 | 欧梯恩智能科技(苏州)有限公司 | Adjustable photodetector, method of manufacture, and wavelength demodulation system |
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| CN1326104A (en) | 2001-12-12 |
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