CN1188914C - InGaAs/InP PIN photo electric detector and its manufacturing technology - Google Patents

InGaAs/InP PIN photo electric detector and its manufacturing technology Download PDF

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CN1188914C
CN1188914C CNB021546061A CN02154606A CN1188914C CN 1188914 C CN1188914 C CN 1188914C CN B021546061 A CNB021546061 A CN B021546061A CN 02154606 A CN02154606 A CN 02154606A CN 1188914 C CN1188914 C CN 1188914C
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inp
diffusion
zinc
ingaas
film
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CN1414642A (en
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陈朝
刘宝林
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Xiamen University
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Abstract

The present invention relates to a semiconductor device, particularly to an InGaAs/InP PIN photoelectric detector for converting an optical signal to an electrical signal and a manufacture process of the photoelectric detector. The InGaAs/InP PIN photoelectric detector is in a quadrilayer double heterojunction material structure which has four layers of double heterojunction materials: an i-InP top layer, an i-In#-[0.53]Ga#-[0.47]As photosensitive layer, an i-InP buffer layer and an N#+[+]-InP substrate., wherein the top layer has a P#+[+] zinc diffusion layer which approaches to the i-In#-[0.53]Ga#-[0.47]As photosensitive layer, but does not reach the photosensitive layer. The process has the following steps that an aluminium oxide passivation film grows on an epitaxial wafer, zinc is used as a diffusion source to diffuse pipe opening zinc, and a direct evaporation method is used for depositing a high quality alumina film on an InP material. The present invention has the advantages of reduced dark current, enhanced signal to noise ratio, easy preparation, low cost and improved structure; the new process of the diffusion of the pipe opening zinc is continuously and simply carried out under the low temperature, and the film can be used as a deactivation film of the InP material and a screening mask which is diffused by zinc, and can also be used as an antireflective film of the InP material, and the performance of the detector is enhanced.

Description

InGaAs/InP PIN photodetector and manufacturing process thereof
(1) technical field
The present invention relates to a kind of semiconductor device, especially a kind of InGaAs/InP (indium gallium arsenic/indium phosphide) PIN photodetector and manufacturing process thereof that light signal is converted to the signal of telecommunication.
(2) background technology:
Photodetector is the semiconductor device that light signal is converted to the signal of telecommunication, is used for the system of optical-fibre communications, computer network, cable TV network and various photo-electric control, photodetection.Photodetector mainly contains PIN and two kinds of structures of APD (avalanche diode).The former only surveys and does not amplify, and works under-5V reverse biased usually; The latter surveys and amplifies simultaneously, must work under bias voltage at height.The photodetector of working under 1310～1550nm long wavelength generally adopts the InGaAs/InP material.The PIN photodetector is under low pressure worked, and responsiveness height, signal to noise ratio are good, easy to use, are photodetectors the most frequently used in the domestic and international optical communication.
Existing InGaAs/InP PIN photodetector (referring to Fig. 1) is at N +Use the InP resilient coating 2 of metal organic chemical vapor deposition (MOCVD) or the non-doping of liquid phase epitaxy (LPE) method growth one deck on-InP (indium phosphide) substrate 1, again the i-In of the non-doping that growth one deck and InP lattice mate mutually on resilient coating 0.53Ga 0.47As (wherein i represents insulation, and In is an indium, and Ga is a gallium, and As is an arsenic) photosensitive layer 3, and then the i-InP top layer 4 of the non-doping of growth one deck form i-InP top layer/i-In 0.53Ga 0.47As photosensitive layer/i-InP resilient coating/N +Four layers of double heterojunction material structure of-InP substrate.If the employing planer device structure, so usually on cleaned epitaxial wafer with cryochemistry vapor deposition (CVD) or enhancement mode plasma chemical vapor deposition (PECVD) method one deck SiO that grows successively 2(silicon dioxide) film and Si 3N 4(silicon nitride) film is as diffusion mask 5.Then, adopt photoetching technique at SiO 2And Si 3N 4Window 6 of selective etching on the mask with the method for stopped pipe zinc diffusion, passes the i-InP top layer with Zn (zinc) from window and is diffused into i-In 0.53Ga 0.47The front end of As photosensitive layer constitutes P +Zn diffusion region 7.Thereby form P +-InP/P +-In 0.53Ga 0.47As/i-In 0.53Ga 0.47As/i-InP/N +The PIN structure of-InP adopts vacuum evaporation or magnetically controlled sputter method to plate Au-Zn/Au (gold-zinc/gold) or Ti/Pt/Au (titanium/platinum/gold) P-type Ohm contact electrode material 8 on the surface of diffusion again, adopts photoetching technique to form photosurface and required figure.On photosurface, form certain thickness Si with vacuum evaporation or magnetically controlled sputter method 3N 4As anti-reflective film 9.Thinning back side causes about 250 μ m, and AuGeNi/Au (gold germanium nickel/gold) N-type Ohm contact electrode material 10 is gone up in evaporation again.At last slice, thin piece is placed in the protective gas and heats 10 minutes formation ohmic contact down in 450 ℃.This conventional InGaAs/InP PIN photodetector structure and technology are seen document ([1] Li Baogen, Xu Zhitao, Zhao Xianming, " have high-quantum efficiency, low Planar InGaAs PIN photodiode " by electric current, high reliability, " optical communication research ", 1994,1～2:124～129.[2] PRODUCT CATALOG (catalogue), P.40. WUHAN TELECOMMUNICATION DEVICES Co., P.35, P.36, ask for an interview Website: Http:// www.wtd.com.cn[3] Zhang Yanbin, Li Shihai, Zhang Shengqiong etc., solid electronics research and progress, 1985,5, (3): 189～198.[4] Photon 2001/2002 optical fiber communication device products handbook, the 4th edition, Shenzhen Photon Technology Co., Ltd., the 3rd page.Ask for an interview Website: Http:// www.photontec.com.cn).
The technological process of existing stopped pipe zinc diffusion is the single-ended open ended quartz tube in the two chambers of blowing.It is two indoor that diffuse source and slice, thin piece are put into quartz ampoule respectively, and vacuumize the seal of tube, carries out two warm areas diffusions then, cracks quartz ampoule after the diffusion and take out slice, thin piece.
In sum, existing InGaAs/InP PIN photodetector is because deficiency on structure and manufacturing process, cause have that dark current is big, responsiveness is on the low side, performance is stable inadequately and cost than problems such as height.
(3) summary of the invention
The purpose of this invention is to provide a kind of dark current and obviously reduce, signal to noise ratio obviously improves, the InGaAs/InP PIN photodetector of easily preparation, with low cost, architecture advances.
Another object of the present invention provides that cost is low, spillage of material is low, the open pipe zinc diffusion new technology that can carry out continuously at a lower temperature, easy, and with the direct aluminum oxide film of method depositing high-quality on the InP material of evaporation, this film can be used for the shield mask of InP material passivation film and zinc diffusion, the anti-reflective film that also can be used for the InP material, the performance of raising detector.
Said InGaAs/InP PIN photodetector is i-InP top layer/i-In 0.53Ga 0.47As photosensitive layer/i-InP resilient coating/N +Four layers of double heterojunction material structure of-InP substrate promptly are provided with N +-InP substrate is at N +Be the InP resilient coating of the non-doping of one deck on the-InP substrate, on resilient coating, be the i-In of the non-doping of mating mutually with the InP lattice 0.53Ga 0.47As photosensitive layer, top layer are the i-InP layer of non-doping.P is arranged in top layer +The zinc diffusion region, P +The zinc diffusion region is near i-In 0.53Ga 0.47The As photosensitive layer, but do not arrive photosensitive layer.In topsheet surface is passivating film, and said passivating film is one deck Al of topsheet surface growth 2O 3(aluminium oxide) film.Preparation P type ohmic contact tunic on diffusion region and passivating film.The bottom of substrate is a N type ohmic contact layer.
The manufacturing technology steps of said InGaAs/InP PIN photodetector is:
1, epitaxial wafer cleans;
2, growth aluminium oxide passivation film on epitaxial wafer;
3, aluminium oxide passivation film photoetching corrosion is formed the diffusion window;
4, carry out the diffusion of open pipe zinc with zinc as diffuse source;
5, in the flow behind the diffusion zinc, generate P +The ohmic contact of-type;
6, with the photosensitive incidence window of metal lithographic on flow surface;
7, at flow surface evaporation pellumina;
8, with window of the pellumina photoetching corrosion on the metal film, for the usefulness of welding P-type electrode;
9, with the back side (substrate) attenuate of flow, be convenient to scribing;
10, generate the ohmic contact of N-type at the back side of flow;
11, form P-type and N-type Ohm contact electrode;
12, behind the upper/lower electrode alloy to flow test, classification, scribing.
Compare with existing InGaAs/InP PIN photodetector, structure of the present invention and manufacturing process have it significantly progressive.
1) utilizes the separation effect of double heterojunction new construction, reduce dark current
Present design is that zinc is diffused in the i-InP top layer near i-In 0.53Ga 0.47As photosensitive layer place, but photosensitive layer do not arrived.Form P +-InP (top layer)/i-InP/i-In 0.53Ga 0.47As (photosensitive layer)/i-InP (photosensitive layer)/N +The PIN double-heterostructure of-InP (substrate).When the PIN pipe is applied-during the reverse operation bias voltage of 5V, make P +The depletion layer thickness of I knot increases and arrival i-In 0.53Ga 0.47In the As photosensitive layer.Can utilize the separation effect of heterojunction like this, reduce the dark current of device greatly.Because the same with conventional structure, incident light still can be at i-In 0.53Ga 0.47Produce photo-generated carrier in the As photosensitive layer, but its dark current greatly reduces.
The dark current J of photodetector dMainly by dark current Jv in the body and surperficial dark current J sTwo parts are formed.Detector for well-designed and desirable cleaning procedure preparation is got on very well, and the surface recombination dark current can be reduced to minimum.Dark current Jv is by generation-recombination current J in the body G-r, dissufion current J DifWith tunnel current J TunForm Deng three parts.From the semiconductor device theory, can prove: J G-r, J DifAnd J TunThis three parts dark current all with the intrinsic carrier concentration n of material iBe directly proportional the n of material iBy its energy gap Eg decision, have n i = N C N V e - Eg / 2 KT Relation.So it is closely-related that dark current that we can say photodetector is that the energy gap with material has, the energy gap of material is big more, and the dark current of device is more little.Calculating shows under the influence of not considering surface recombination, the dark current In more less than energy gap that the InP that energy gap is bigger (under the room temperature, Eg ≈ 1.34ev) is produced 0.53Ga 0.47As (under the room temperature, Eg ≈ 0.75ev) low about 3.85 * 10 4Doubly.So under same process conditions, the dark current of pressing this programme design will be more much smaller than the dark current of structural design preparation routinely.For the detector of 75 microns of photosensitive diameters, dark current generally all reaches below the 0.1nA than being easier to.
Its principle is as follows:
The signal to noise ratio that improves photodetector just must reduce the dark current of device as far as possible.In general, the dark current J of photodetector dBy dark current Jv in the body and surperficial dark current J sTwo parts are formed.By well-designed and preparation technology cleaning surfaces,, surperficial dark current partly can be reduced to minimum as plane passivation, guard ring, ultra-clean technology etc.Dark current Jv is by generation-recombination current J in the body G-r, dissufion current J DifWith tunnel current J TunForm.Generation-recombination current J G-rCan be expressed as:
J G-r=(qn iAW/ τ e) [1-exp (qV/kT)] (1) wherein, q is an electron charge, n iBe the intrinsic carrier concentration of material, A is a light-receiving area, and W is a depletion width, τ eBe the efficient carrier life-span, V is a bias voltage, and T is an absolute temperature.Dissufion current J DifCan be expressed as:
J dif＝J′ dif[1-exp(-qV/KT)] (2)
Wherein, J ' DifBe the dissufion current that produces in P district or the N district, they are respectively:
J ' is arranged for the P district Dif, p=qn i 2(D p/ τ p) 1/2(A n/ N D) (3)
J ' is arranged for the N district Dif, n=qn i 2(D n/ τ n) 1/2(A p/ N p) (4)
Wherein, D p, D n, τ p, τ n, A p, A nAnd N p, N nBe respectively hole and electron diffusion coefficient, life-span, light-receiving area and concentration.
Tunnel current J TunIts importance that just seems under high electric field and heavy doping situation is obvious not as APD for the contribution of PIN photodetector dark current.As above analyze as can be known, produce a recombination current J in the PIN photodetector dark current G-rIntrinsic carrier concentration n with material iBe directly proportional dissufion current J DifIntrinsic carrier concentration n with material iSquare be directly proportional.The intrinsic carrier concentration n of material iEnergy gap E by material gWith temperature decision: n i = N C N V e - Eg / 2 KT , Wherein, N CAnd N VBe respectively at the bottom of the conduction band of material and the equivalent density of states of top of valence band.The E of InP at room temperature gBe 1.34ev, intrinsic carrier concentration n iBe 1.4 * 10 7Cm -3In at room temperature 0.53Ga 0.47The E of As gBe 0.75ev, intrinsic carrier concentration n iBe 5.4 * 10 11Cm -3
Obviously, for existing InGaAs/InP PIN detector, because with P +The district is produced on energy gap E gLess In 0.53Ga 0.47In the As photosensitive layer material, intrinsic carrier concentration n iBigger.And InGaAs/InP PIN detector of the present invention, because with P +The district is produced on energy gap E gIn the bigger InP quilting material, intrinsic carrier concentration n iLess.Under light-receiving area, layers of material doping content and all identical situation of thickness, material temperature, process conditions, calculating InGaAs/InP PIN detector dark current density of the present invention by above-mentioned formula (1) and (2) will be than existing InGaAs/InP PIN detector much lower (about 3.85 * 10 4Doubly).
2) zinc diffusion technology: the present invention adopts open pipe zinc diffusion technology, and common process adopts stopped pipe zinc diffusion technology.
Open pipe zinc diffusion of the present invention adopts high purity zinc (Zn, 99.999%) as diffuse source, and its price is than stopped pipe zinc diffuse source ZnP 2(two zinc phosphides) is much lower, has also bought easily.The diffusion of open pipe zinc is to adopt the half chests method to carry out on the diffusion furnace of single warm area, the sample surfaces light after the diffusion, and available Electrochemical C-V (capacitance-voltage) tester, the surface voids concentration that measures sample is 7.5 * 10 18Cm -3, tie lines is smooth, and junction depth is～0.5 μ m.If open pipe diffusion zinc in enormous quantities then can insert a plurality of epitaxial wafers in quartz boat vertically.Obviously open pipe zinc diffusion technology can be at a lower temperature continuously, carry out easily, greatly reduce the technology cost and save the process time.
3) aluminium oxide passivation film and anti-reflective film:
Existing InGaAs/InP PIN photodetector technology is at material surface growth one deck SiO 2Film or SiO 2+ Si 3N 4Film plays the passivation protection effect to chip, on the other hand to P on the one hand as passivating film +The selection of-type zinc impurities has been spread and has been stopped and masking action.
SiO 2Though film has lower interface state density and comparatively desirable electrical parameter, but its short texture, shielding action to impurity Zn diffusion is not really desirable, causes problems such as dark current increase, reverse breakdown voltage reduction, unstable properties, and this has just had a strong impact on the performance of device; Si 3N 4The interface state density of film is than SiO 2Film is high slightly, and its insulation property and shielding action are good, but its investment in production equipment is higher, and production process is complicated, is unfavorable for the reduction of production cost; And at SiO 2Regrowth one deck Si on the film 3N 4Film forms SiO 2+ Si 3N 4Bilayer film is as passivating film, and its effect is than the SiO of individual layer 2Film and Si 3N 4Film is all good, but SiO 2+ Si 3N 4Bilayer film has increased the complexity in passivating film growth and selective etching, and production cost increases.
The present invention selects Al 2O 3Film is as the passivating film of InGaAs/InP PIN photodetector.It is compact structure not only, selects stopping with masking effect of diffusion good to zinc, and insulation property and moisture resistance gas ability are all good, and leakage current is little, and at Al that chip surface forms 2O 3The interface state density at/InP interface is very little (less than 5 * 10 11Cm -2), surface recombination is reduced, dark current reduces.Can produce preparation with the simplest equipment, promptly therefore direct heat evaporation can guarantee the various performances of device on basis very cheaply on substrate under the less demanding situation of vacuum degree.
Existing InGaAs/InP PIN photodetector, evaporation growth SiO on the chip incidence window 2Or SiO 2+ Si 3N 4Film to reduce the reflection of incident light at chip surface, improves chip to absorption of incident light as anti-reflective film.And the present invention selects to use Al 2O 3Film is as the anti-reflective film of chip, and antireflecting effect compares SiO 2Film or Si 3N 4Film is good.This is because of the principle according to the individual layer anti-reflective film, reaches minimum in order to make reflection loss, promptly wishes r=0, must satisfy d=λ/4n aWith n a = n 0 n InP Two conditions, wherein, d is the thickness of reflectance coating, λ is lambda1-wavelength (being 1310nm), n a, n 0And n InPIt is respectively the refractive index of anti-reflective film, air and InP material.Known n 0≈ 1, for 1310-1550nm, and n InP≈ 3.3.Therefore, the refractive index n of Zui Jia deielectric-coating aShould be 1.82.The Al that we grew 2O 3The refractive index of deielectric-coating just between 1.7-1.8, meets best antireflection designing requirement.And unformed SiO 2And Si 3N 4Refractive index, be respectively 1.46 and 2.05, do not meet best antireflection designing requirement, need to adopt the multilayer design, this has obviously increased chip cost.
Common Al 2O 3The method of film growth has sol-gel process, mocvd method, AlCl 3(alchlor) Hydrolyze method, reactive sputtering, anodic oxidation etc., these methods exist or apparatus expensive or not wield problem.The present invention proposes to adopt general vacuum coating equipment with high-purity Al 2O 3Powder directly is evaporated to the method on the sample.Test shows that equipment of the present invention is simple, Al 2O 3The quality of film is good, meets the passivation mask of InGaAs/InP PIN photodetector and the requirement of anti-reflective film.
Since oxide evaporation the time generally can produce decompose or with heating appliances generation chemical reaction, so seldom prepare sull usually with the method for directly evaporation.Though we consider Al 2O 3Need evaporate under 2000 ℃ of left and right sides high temperature, it at high temperature decomposes (Al in the time of 1781 ℃ hardly 2O 3Decomposition pressure only have 1.5 * 10 -8Torr).But at Al more than 2000 ℃ 2O 3Can be reduced by tungsten material commonly used.Because the fusing point of metal molybdenum is 2610 ℃, Al gets along well under 2000 ℃ of left and right sides high temperature 2O 3Chemical reaction takes place.We select for use molybdenum sheet to make boat shape container, with high-purity Al 2O 3Powder is packed in the molybdenum boat.When leading to big electric current on the aluminium boat, can not make Al 2O 3Powder is contaminated.10 -5In the vacuum chamber of torr, if we are being equipped with the high-purity Al of employing 2O 3When carrying out Fast Heating by big electric current on the molybdenum boat of powder, Al 2O 3Powder will be evaporated on the substrate frame of vacuum chamber top.In the environment of vacuum, Al 2O 3The production process of film is subjected to the influence of external environment little, can access stable growth conditions, is easy to control, can be in enormous quantities, evaporation in large area and repeatability, uniformity be all fine.
(4) description of drawings
Fig. 1 is the structural representation of existing InGaAs/InP PIN photodetector.
Fig. 2 is the structural representation of InGaAs/InP PIN photodetector of the present invention.
Fig. 3 is an open pipe zinc diffusion schematic diagram of the present invention.
Fig. 4 is a multi-disc open pipe zinc diffusion boat schematic diagram of the present invention.
Fig. 5 is a vacuum coating equipment vapo(u)rization system schematic diagram.
Fig. 6 is the molybdenum boat structural representation.
Fig. 7 is Al 2O 3The interface scintigram of/InP.
Fig. 8 is Al 2O 3The surface scan figure of film.
(5) embodiment
As shown in Figure 2, InGaAs/InP PIN photodetector new construction of the present invention is:
I-InP top layer 14/i-In 0.53Ga 0.47As photosensitive layer 13/i-InP resilient coating 12/N +11 4 layers of double heterojunction material structure of-InP substrate.On i-InP top layer 14, directly evaporate Al 2O 3Passivating film film 19, and a diffusion of photoetching window 16 are made P with the i-InP top layer of open pipe method of diffusion in window +Zinc expands, and makes diffusion region 17 near i-In 0.53Ga 0.47As photosensitive layer 13 is at diffusion window and Al 2O 3Evaporate Au/Zn and Ti/Al on the passivating film and make the incident light window by lithography and P-type Ohm contact electrode 18.Bottom is a N-type ohmic contact layer 20, adopts the AuGeNi alloy-layer.
Preparation technology's process description of InGaAs/InP PIN photodetector is as follows.
Be ready to use the epitaxial wafer of LP-MOCVD (low pressure-Organometallic chemical vapor deposition) growth by designing requirement.Epitaxial wafer is successively after toluene → acetone → ethanol → deionized water is cleaned, and after washing repeatedly with deionized water, with the absolute ethyl alcohol dehydration, nitrogen dries up standby.(annotating:, directly standby) if epitaxially grown slice, thin piece can clean through encapsulation process.
Growth one layer thickness is about 2000 , shows the aluminium oxide passivation film of deep sky blue on the epitaxial surface of the light of epitaxial wafer.With first reticle and negative photoresist, with conventional photoetching process, with window of aluminium oxide passivation film photoetching corrosion, for the usefulness of zinc diffusion.The corrosive liquid of aluminium oxide, the hot phosphoric acid with 80% corrodes 30～60s under 80 ℃ of water-baths.Corrosion rate is about 1500～2000 /min.Should note and the aluminium oxide passivation mask must be corroded totally fully.This can be judged that window should show the Dark grey of epitaxial wafer by the color of window, and can not show the sky blue of aluminum oxide film.The resistance of yet available universal instrument measurement window, if resistance is very big, corrosion is unclean to show pellumina.
Accompany the charge carrier distribution of sheet to measure after the reply diffusion, check accompanies the hole concentration of sheet and junction depth whether to satisfy designing requirement.The PN4300 type Electrochemical C-V carrier concentration profile instrument that available Bio Rad Laboratories produces is measured the hole and is vertically distributed.The also potassium hydroxide solution of available iron potassium cyanide dyeing is measured junction depth with measuring microscope.Use the four-point probe measurment square resistance.
With the method for vacuum vapor plating or magnetron sputtering,, be used to form P successively covering Au/Zn alloy and Ti/Al double-level-metal in the flow behind the diffusion zinc +The ohmic contact of-type preferably adopts electron beam evaporation, and vacuum degree should be higher than 10 -5Torr reduces as far as possible, and the pollution of oil prevents coming off of metal film.When using magnetron sputtering, can adopt two kinds of frequencies of height respectively, the mismatch stress on metal and the pellumina is released.Adopt second reticle, with negative photoresist and conventional photoetching process, with a photosensitive window of metal lithographic on flow surface.Metal etch can be selected plasma dry method or wet chemical.Whether chemical corrosion liquid can adopt the iodine solution of KI, at room temperature carries out, corrode totally with the metal on the microscopically observation window.
Inch aluminium oxide anti-reflective film can adopt direct method of evaporating in the surface evaporation of flow, measures the thickness and the refractive index of aluminum oxide film with ellipsometer test.
With the 3rd block of reticle and negative photoresist, with the window of aluminium oxide anti-reflective film photoetching corrosion on the metal film, for the usefulness of welding P-type electrode.The corrosive liquid of aluminium oxide, the hot phosphoric acid with 80% corrodes 30-60s under 80 ℃ of water-baths.Corrosion rate is about 1500～2000 /min.Should note and alumina mask must be corroded totally fully.This can be judged that window should show the Dark grey of epitaxial wafer by the color of window, and can not show the sky blue of aluminum oxide film.The resistance of yet available universal instrument measurement window, if resistance is very big, corrosion is unclean to show pellumina.With the back side (substrate) of flow, so that reduce serial resistance, be convenient to scribing with mechanical lapping.Flow after the grinding is successively after toluene → acetone → ethanol → deionized water is cleaned, and after washing repeatedly with deionized water, with the absolute ethyl alcohol dehydration, nitrogen dries up standby.The flow back side behind the attenuate is with the method for vacuum evaporation or magnetron sputtering, deposit layer of Au-Ge-Ni (or Au-Ge) alloy firm.Wherein, Au 83%, and Ge 12%, Ni 5% (or Au account for 88%, Ge accounts for 12%).Preferably adopt electron beam evaporation, vacuum degree should be higher than 10 -5Torr reduces as far as possible, and the pollution of oil prevents coming off of metal film.In the protective atmosphere of nitrogen and hydrogen, flow under 400-450 ℃, is heated about 10min, form P-type and N-type Ohm contact electrode.Should lead to N earlier during operation 2Logical H behind the gas 2Gas should close H earlier behind the alloy 2N is closed in the back 2Gas.
Operations such as the flow behind the alloy can be tested, classification, scribing are finished entire chip manufacturing process.
Referring to Fig. 3, open pipe zinc diffusion is to adopt the half chests method to carry out on the diffusion furnace 21 of single warm area, and wafer 22 and metallic zinc 23 are placed in the quartz boat 24 that contains lid, quartz boat is placed in the quartz ampoule 25 of both ends open again and opens nitrogen (N 2, dew point is-56 ℃) and hydrogen (H 2, dew point is-60 ℃) and as protective atmosphere.The temperature of diffusion is 460-480 ℃, and the time of diffusion is about 30 minutes, N 2And H 2Flow be respectively 10-12ml/min and 3-5ml/min.After arriving diffusion time, quartz boat shifted onto the quartz ampoule exit and stop 5min take out again.Sample surfaces light after the diffusion, available Electrochemical C-V tester, the surface voids concentration that measures sample is 7.5 * 10 18Cm -3, tie lines is smooth, and junction depth is～0.5 μ m.If open pipe diffusion zinc in enormous quantities then can insert in quartz boat 24 (referring to Fig. 4) vertically with a plurality of epitaxial wafers 22,23 of high-purity zinc granules are placed in the groove of diffuse source in the boat, once can put about 1 gram.After putting epitaxial wafer and zinc granule well, the sleeve pipe 26 that seals molybdenum systems with two one ends packages quartz boat and put into quartz ampoule, logical N 2And H 2Add thermal diffusion behind the protective atmosphere again.Obviously open pipe zinc diffusion technology can be at a lower temperature continuously, carry out easily, greatly reduce the technology cost and saved the process time.
Direct evaporation growth Al of the present invention 2O 3The device of film as shown in Figure 5.
The vacuum coating equipment vapo(u)rization system can adopt vacuum coating equipment, and its major part has: 1) the metal vacuum cover 27 of band window; 2) evaporation source 28 is high-purity Al 2O 3(99.99%) powder is placed in the molybdenum boat 29, and the molybdenum boat two ends are electrode 30; 3) glass or Metal Substrate horse 31, sample substrate sticks on the substrate frame with indium, and evaporating surface is down; 4) pumped vacuum systems is made up of mechanical pump and diffusion pump, and vacuum degree is 10 -5Torr.
The detailed process flow of vacuum evaporation aluminium oxide:
1) cleaning equipment
Before evaporation, need peer device to clear up, to reduce the pollution of impurity to plated film.At first to grind off impurity in the vacuum (-tight) housing, with fine sandpaper fine grinding one time again with rove paper; Utilizing acetone and absolute ethyl alcohol to clean several all the removing totally all over the impurity on vacuum (-tight) housing inwall, substrate frame, electrode, baffle plate etc. then also dries.
2) put evaporation source:
Prepared molybdenum boat shape as shown in Figure 6.After using acetone and absolute ethyl alcohol clean required molybdenum boat 29 and molybdenum filament 32 respectively, molybdenum boat is placed on the electrode, put into high-purity alumina powder 33 after, be wrapped on the molybdenum boat with molybdenum filament, the two poles of the earth of molybdenum boat are clipped on two electrodes.
3) setting-out product:
Sample is successively clean and dry up with toluene → acetone → absolute ethyl alcohol → washed with de-ionized water.The heating indium pellet also makes its fusing, sample is bonded on the specimen holder of glass with the indium that melts at the back side of sample, specimen holder is contained in the top of molybdenum boat again, places baffle plate.
4) evaporation:
Put down vacuum (-tight) housing, open mechanical pump vacuum chamber is vacuumized, when vacuum degree reaches 5 * 10 -2During mmHg, diffusion pump is opened.Through about 30min, vacuum degree reaches 10 -5During mmHg, begin to add electric current heating, slowly strengthen heating current, make Al thereby prevent to heat too fast, the inequality of being heated 2O 3Powderject comes out.When electric current is added to 250A, Al 2O 3Powder evaporation clearly, at this moment the measured vacuum degree of vacuum measuring gauge obviously descends, and removes that the evaporation duration is 10min behind the baffle plate.At this moment the back temperature that records specimen holder with thermocouple is about 100 ℃.Turn-off the heated by electrodes electric current, turn-off diffusion pump and mechanical pump.Sample is being opened vacuum (-tight) housing behind the natural cooling 1s under the environment of vacuum, takes out specimen holder.With thermoelectric wind heated sample frame the indium at the sample back side is melted, take out sample then.
5) measure:
1. Al 2O 3The measurement of film thickness and refractive index:
Utilize the Al of ellipsometer test to being grown 2O 3The thickness of film is measured, and all about 1000-2000nm, refractive index is the scope of 1.7-1.9 to the thickness that records.Utilizing resolution is the thickness of the HITACHI S-520 scanning electron microscopy measurement film of 50 , under 15000 times enlargement ratio, and the Al that is evaporated 2O 3Film thickness is approximately 1500nm, in the scope of 1000-2500nm.
2., Al 2O 3The structure of film
Al under 15000 times high magnification scanning electron microscopy 2O 3The surface texture figure of film is shown in Fig. 7,8.Can observe from photo, the densification very of this surface does not have other impurity structure to show.
Relatively seeing the following form of device performance of the present invention and similar products at home and abroad.
InGaAs/InP PIN photodetector (is example with 70 microns of photosurface diameter of phi)
Task and manufacturer Operation wavelength Responsiveness S Dark current Is Electric capacity pf/-5v Response time
Performance of the present invention 900～1600 nm ≥0.85A/W(1310nm) ≥0.95A/W(1550nm) 0.1～1.0nA (Vr＝5V) 0.7-1.0pf t≤100ps (Vr＝5V)
Shenzhen Photon photoelectron 1100～1600 nm ≥0.8A/W (1310nm) Typical case: 1nA, maximum: 5nA (Vr=5V) 0.75pf tr，tf 100ps
Wuhan telecommunications WTD 1100～1650 nm ≥0.8A/W (1310nm) ≤5nA (Vr＝5V) 1.0pf Rise time tr 500ps
13 XO of information portion (17) (PD75) 1310 nm 0.85-0.95A/W (1310nm) 0.15～1.0nA (Vr＝5V) 0.5-0.7 -
Jin Ke (platform) TPD-1c12-001 1310nm 0.9A/W (1310nm) 0.1～1nA (Vr＝5V) 0.7-0.8pf -
Kyoto, Japan Kyoto KPDE008C 1310～1550 nm 0.8-0.9A/W (1310nm) 0.03～0.3nA (Vr＝5V) 0.6-1.2pf -
U.S. Microsemi., MXP4002 1310～1550 nm 0.8A/W (1310nm) 0.95～1.0A/W (1550nm) 2.0nA (Vr＝5V) 0.5pf -

Claims (9)

1, InGaAs/InP PIN photodetector is characterized in that top layer/i-In for i-InP 0.53Ga 0.47As photosensitive layer/i-InP resilient coating/N +Four layers of double heterojunction material structure of-InP substrate promptly are provided with N +-InP substrate is at N +Be the InP resilient coating of the non-doping of one deck on the-InP substrate, on resilient coating, be the i-In of the non-doping of mating mutually with the InP lattice 0.53Ga 0.47As photosensitive layer, top layer are the i-InP layer of non-doping; P is arranged in top layer +The zinc diffusion region, P +The zinc diffusion region is near i-In 0.53Ga 0.47The As photosensitive layer, but do not arrive photosensitive layer; In topsheet surface is passivating film, and said passivating film is one deck Al of topsheet surface growth 2O 3Film: preparation P type ohmic contact tunic on diffusion region and passivating film; The bottom of substrate is a N type ohmic contact layer.
2, the manufacturing process of InGaAs/InP PIN photodetector is characterized in that the steps include:
1), epitaxial wafer cleans;
2), growth aluminium oxide passivation film on epitaxial wafer;
3), aluminium oxide passivation film photoetching corrosion is formed the diffusion window;
4), carry out the diffusion of open pipe zinc as diffuse source with zinc;
5), in the flow behind the diffusion zinc, generate P +The ohmic contact of-type;
6), with the photosensitive incidence window of metal lithographic on flow surface;
7), at flow surface evaporation pellumina;
8), with window of the pellumina photoetching corrosion on the metal film, for the usefulness of welding P-type electrode;
9), with the thinning back side of flow, be convenient to scribing;
10), generate the ohmic contact of N-type at the back side of flow;
11), form P-type and N-type Ohm contact electrode;
12), behind the upper/lower electrode alloy to flow test, classification, scribing.
3, the manufacturing process of InGaAs/InP PIN photodetector as claimed in claim 2 is characterized in that the zinc diffusion technology adopts open pipe zinc diffusion technology, adopts high purity zinc as diffuse source.
4, the manufacturing process of InGaAs/InP PIN photodetector as claimed in claim 3 is characterized in that said open pipe zinc diffusion is to adopt the half chests method to carry out on the diffusion furnace of single warm area.
5, the manufacturing process of InGaAs/InP PIN photodetector as claimed in claim 3 is characterized in that said open pipe zinc diffusion, a plurality of epitaxial wafers can be inserted in quartz boat vertically.
6, the manufacturing process of InGaAs/InP PIN photodetector as claimed in claim 3, it is characterized in that open pipe zinc diffusion is that diffusion furnace (21) at single warm area is gone up and adopted the half chests method to carry out, wafer (22) and metallic zinc (23) are placed in the quartz boat (24) that contains lid, again quartz boat is placed in the quartz ampoule (25) of both ends open and open nitrogen and hydrogen as protective atmosphere; The temperature of diffusion is 460-480 ℃, N 2And H 2Flow be respectively 10-12ml/min and 3-5ml/min; After arriving diffusion time, quartz boat shifted onto the quartz ampoule exit and stop 5min take out, be 30min diffusion time.
7, the manufacturing process of InGaAs/InP PIN photodetector as claimed in claim 2 is characterized in that selecting Al 2O 3Film is as the passivating film of InGaAs/InP PIN photodetector.
8, the manufacturing process of InGaAs/InP PIN photodetector as claimed in claim 2 is characterized in that adopting vacuum coating equipment with high-purity Al 2O 3Powder directly is evaporated on the sample.
9, the manufacturing process of InGaAs/InP PIN photodetector as claimed in claim 2 is characterized in that selecting for use molybdenum sheet to make boat shape container, with high-purity Al 2O 3Powder is packed in the molybdenum boat.
CNB021546061A 2002-11-25 2002-11-25 InGaAs/InP PIN photo electric detector and its manufacturing technology Expired - Fee Related CN1188914C (en)

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