1、2021/2/13 SaturdayTSSEL part-1-MOVPE growth.ppt - version 1.0第第 8 章章 AlGaInP 发光二极管发光二极管 AlGaInP 2021/2/13 SaturdayTSSEL part-1-MOVPE growth.ppt - version 1.0Introduction to MOCVD/MOVPE/OMVPE2021/2/13 SaturdayTSSEL part-1-MOVPE growth.ppt - version 1.0MOCVD/MOVPE/OMVPE MOCVD: Metal Organic Chemical V
2、apor Deposition MOVPE:Metal Organic Vapor Phase Epitaxy OMVPE:Organo Metallic Vapor Phase Epitaxy Often all three expressions are used interchangeablyMOCVD实例实例二、二、LED外延片的制作外延片的制作系统简介系统简介 本系统为英国本系统为英国Thomas Swan公司制造，具有世公司制造，具有世界先进水平的商用金属有机源气相外延界先进水平的商用金属有机源气相外延(MOCVD)材料生长系统，可用于制备材料生长系统，可用于制备GaAs和和InP
3、、GaN为为代表的第二、三代半导体材料。在高亮度的蓝光代表的第二、三代半导体材料。在高亮度的蓝光发光二极管发光二极管(LED)、激光器、激光器(LD)、日盲紫外光电探、日盲紫外光电探测器、高效率太阳能电池、高频大功率电子器件测器、高效率太阳能电池、高频大功率电子器件领域中具有广泛的应用。领域中具有广泛的应用。 二、二、LED外延片的制作外延片的制作 MOCVD已经成为工业界主要使用的镀膜技术。已经成为工业界主要使用的镀膜技术。 使用使用MOCVD这种镀膜技术制作这种镀膜技术制作LED的外延片，即的外延片，即在衬底上镀多层膜。在衬底上镀多层膜。 外延片是外延片是LED生产的上游产业，在光电产业中
4、扮生产的上游产业，在光电产业中扮演重要的角色。演重要的角色。 有些专家经常用一个国家或地区拥有有些专家经常用一个国家或地区拥有MOCVD外延外延炉的数量来衡量这个国家或地区的光电行业的发炉的数量来衡量这个国家或地区的光电行业的发展规模。展规模。二、二、LED外延片的制作外延片的制作2021/2/13 SaturdayTSSEL part-1-MOVPE growth.ppt - version 1.0The World of Semiconductors III IV VCompound semiconductorsIII-Vs: GaAs, AlGaAs, GalnP,AlGaInP, Ga
5、N, InGaNSpeciality: SiCTraditional semiconductorsSi: DRAMs, processorsAdvantages of compound semiconductors: faster, higher frequencies visible light, infrared high efficient photovoltaics heat and high power resistantEnabling technology for:2021/2/13 SaturdayTSSEL part-1-MOVPE growth.ppt - version
6、1.0How MOCVD Works2021/2/13 SaturdayTSSEL part-1-MOVPE growth.ppt - version 1.0Components of a Low Pressure (LP) MOCVD Systemgas control unitreactor with heated susceptorvacuum systemcontrolunitscrubbing system2021/2/13 SaturdayTSSEL part-1-MOVPE growth.ppt - version 1.0Simplified Presentation of a
7、Crystal Growth Process2021/2/13 SaturdayTSSEL part-1-MOVPE growth.ppt - version 1.0Basic Principle of the MOVPE Process A gas mixture containing the precursors needed for growth, and if necessary for doping, is passed over a heated substrate. The precursor molecules pyrolyze(使裂解) leaving the atoms,
8、e.g., Ga and As atoms on the substrate surface. The atoms bond to the substrate surface and a new crystalline layer is grown, in this case GaAs.2021/2/13 SaturdayTSSEL part-1-MOVPE growth.ppt - version 1.0Precursors2021/2/13 SaturdayTSSEL part-1-MOVPE growth.ppt - version 1.0Sample: Precursor Molecu
9、lesAsH3DMZn - (CH3)2ZnTMGa - (CH3)3GaHCAsZnGa8.11 源材料（源材料（Precursors）2021/2/13 SaturdayTSSEL part-1-MOVPE growth.ppt - version 1.0MOCVD Precursors Desirable properties of precursors: Low toxicity Liquid at room temperature Suitable vapor pressure at room temperature Low carbon contamination in grown
10、 layer (avoid CH3 radicals), however, for some applications C doping is desired (though rarely achieved by autodoping techniques. No parasitic reactions with other sources Good long term stability (should not decompose in bubbler) Pyrolysis temperature should match the ideal growth temperature Inexp
11、ensive for industrial mass production2021/2/13 SaturdayTSSEL part-1-MOVPE growth.ppt - version 1.0Group III MO PrecursorsPrecursor Symbol Advantages Disadvantages TMGa (CH3)3Ga liquid, high vapor pressure TEGa (C2H5)3Ga liquid, low carbon contamination, decomposes by -hydride elimination reaction, u
12、sed in LP MOVPE systems low vapor pressure, less stable than TMGa, strong parasitic reactions TMIn (CH3)3In solid, good vapor pressure for MOVPE low vapor pressure TEIn (C2H5)3In very unstable TMAl (CH3)3Al liquid, good vapor pressure, good long term stability oxygen contamination TEAl (C2H5)3Al liq
13、uid, low carbon contamination low long term stability 2021/2/13 SaturdayTSSEL part-1-MOVPE growth.ppt - version 1.0Group III MO Precursors - Bubblers2021/2/13 SaturdayTSSEL part-1-MOVPE growth.ppt - version 1.0Group V PrecursorsPrecursorSymbolAdvantagesDisadvantagesArsineAsH3good pressure control fo
14、r MOVPE,inexpensivevery toxic, highpyrolysis temperature(T50 = 600C)PhosphinePH3good pressure control for MOVPE,inexpensivevery toxic, highpyrolysis temperature(T50 = 850C)TBA(C4H9)AsH2liquid, good vapor pressure for MOVPE,very low carbon contamin., good stability,low pyrolysis temperature (T1/2 = 3
15、80C)expensive for manyapplicationsTEA(C2H5)3Asliquid, used to grow C doped GaAsTBP(C4H9)PH2liquid, good vapor pressure for MOVPE,good stability, low pyrolysis temperature(T1/2 = 450C)expensive for manyapplicationsAmmonia(for nitrides)NH3good stability, only practically availablenitrogen precursorhig
16、h pyrolysistemperature2021/2/13 SaturdayTSSEL part-1-MOVPE growth.ppt - version 1.0Dopant PrecursorsPrecursor Symbol Advantages Disadvantages DMZn (p-dopant) (CH3)2Zn liquid, high vapor pressure, very common Zn precursor Zn often has very high diffusion coefficient in solid, diffuses via interstitia
17、ls Carbontetrachloride (p-dopant in GaAs) CCl4 liquid, C is shallow acceptor in GaAs, C has low diffusion coeff., used for sharp interfaces, e.g., for high p-type doping in HBTs usage might be subject to legal regulation due to ozone depleting character of chemical Carbontetrabromide (p-dopant ) CBr
18、4 used in similar applications as CCl4 same as for CCl4 Silane (n-dopant) SiH4 used as n-dopant for electronic devices gaseous, flammable, high pyrolysis temperature Disilane (n-dopant) Si2H6 used in similar applications as SiH4, but lower pyrolysis temp., better doping uniformity than SiH4 gaseous,
19、 flammable DETe (n-dopant) (C2H5)2Te liquid, used in LED production Hydrazine UDMHy (CH3)2NNH2 Liquid source, used for adding Nitrogen to GaAs materials Very unstable, very flammable Rocket fuel 2021/2/13 SaturdayTSSEL part-1-MOVPE growth.ppt - version 1.0Basic Transport and Growth Mechanisms2021/2/
20、13 SaturdayTSSEL part-1-MOVPE growth.ppt - version 1.0Principle of LP-MOVPEH , N P=100 Torr22TMGa, AsH3TMGa, NH3TMIn , PH3gas blendingreactorhigh purity, precise mixingsafetyGaAs, InP substrate, T 400 - 1000CD100 rpmproduction orientedlow cost of ownershipGa(CH ) + AsH GaAs + 3CH3 334 TMAl, TMGa,sap
21、phireGa(CH ) + NH GaN + 3CH3 334scrubbing systemH2filter unitvacuum pumpthrottle valvecrystal quality, thicknessuniformity, reproducibility2021/2/13 SaturdayTSSEL part-1-MOVPE growth.ppt - version 1.0MOVPE Growth Mechanisms(simplified)boundary layersurface diffusionand reactionincorporationand growt
22、hCH4 =CH3 + HH + H = H2wafer surfacemass transportto the surfaceby diffusionatomic stepHHHAsCH3GaCH3CH3precursordecomposition-radicaladsorptionCH3CH3-radicalgas phasehorizontal gas flowHHHAsGaCH3CH3CH3H2H2H2H22021/2/13 SaturdayTSSEL part-1-MOVPE growth.ppt - version 1.0Example: GaAs Growth Efficienc
23、y102103104Growth Efficiency m/mole1000/T K-10.61.01.4BAC2021/2/13 SaturdayTSSEL part-1-MOVPE growth.ppt - version 1.0Layer GrowthInGaN layers investigated by scanning electron microscopy (SEM), cathodo-luminescence (CL) imaging, high resolution X-ray analysis (EDX) SEMCLEDX2021/2/13 SaturdayTSSEL pa
24、rt-1-MOVPE growth.ppt - version 1.0Basic Device production the steps surrounding MOCVD2021/2/13 SaturdayTSSEL part-1-MOVPE growth.ppt - version 1.0Silicon Wafer ProductionPattern PreparationCrystal PullingSilicon process is more complex,up to 100 process steps, plus measurements at each stage, 50 da
25、y cycle2021/2/13 SaturdayTSSEL part-1-MOVPE growth.ppt - version 1.0OptoElectronics2021/2/13 SaturdayTSSEL part-1-MOVPE growth.ppt - version 1.0LEDs15000 LEDs on a 2“-WaferChip size : 0.35 x 0.35mmThe optoelectronic properties of the different compound semiconductors determine the illuminated color
26、of an LED:red to yellow/green AlGaAs, AlGaInPgreen/blue (In)GaNWhite light is generated by combining blue LEDs with fluorescent dyes.2021/2/13 SaturdayTSSEL part-1-MOVPE growth.ppt - version 1.0GaN LED Test Structures grown on an AIXTRON SystemWith courtesy of National Central University, Taiwan Wit
27、h courtesy of SAIT, KoreaGaN Blue Laser device grown on a THOMAS SWAN System2021/2/13 SaturdayTSSEL part-1-MOVPE growth.ppt - version 1.0What is important for successful Epitaxy? Thermal management in the reactor effects Transport coefficient Reaction rates Incorporation of dopants Composition of mu
28、lticomponent material systems Composition of the gas phase For (AlxGa1-x)0.52In0.48P LEDs the Al/Ga-ratio determines the color of the LED. Therefore calibrated and stable MFCs and PCs are needed for reproducible LED colors. Bubbler temperature determines vapor pressure of MO2021/2/13 SaturdayTSSEL p
29、art-1-MOVPE growth.ppt - version 1.0Products made by MOVPE2021/2/13 SaturdayTSSEL part-1-MOVPE growth.ppt - version 1.0 GaAs AlGaAs InGaP InGaAs InSb MESFETs HEMTs PHEMTs HBTs Lasers Mobile Telephony Global Positioning Systems (GPS) Satellite Systems Direct Broadcast Satellite (DBS) Paging Wireless
30、LAN / Wireless Cable Automotive Radar InP InGaAs InAlAs InGaAlAs InGaAsP InGaAsN DH, QW, DFB Lasers LEDs VCSELs Detectors HBTs Optical Fiber Communications Sensors Infra-Red Cameras Wireless Communications GaAs AlGaAs InGaAs InGaAlAs InGaAsP DH, QW, VCSELs HEMTs FETs Solar Cells Detectors Fiber Ampl
31、ifiers, Gigabit Ethernet Medical Systems Solid State Laser Pumps CD, Minidisc GPS Automotive Satellite Systems InGaP InAlP InAlP GaN InGaN InGaAlN Visible Lasers UHB LEDs Visible VCSELs HBTs DJ Solar Cells Displays DVD / CD Illumination Pointers / Bar Code Wireless Communications Satellite Systems M
32、edical Applications Material SystemsDevicesApplications IQE PLC2021/2/13 SaturdayTSSEL part-1-MOVPE growth.ppt - version 1.0Requirements of Compound Semiconductor Industry Uniformity of layer thickness and composition of 1% on the wafer Temperature uniformity on wafer T = 1C within a wide temperatur
33、e range Wafer to wafer and run to run reproducibility Low cost of ownership, high wafer capacity, high up-time ratio2021/2/13 SaturdayTSSEL part-1-MOVPE growth.ppt - version 1.0Why MOVPE? Very high quality of grown layers (high growth rate and doping uniformity/reproducibility) High throughput and n
34、o ultra high vacuum needed (compared to MBE), therefore economically advantageous, high system up-time Different materials can be grown in the same system, therefore highest flexibility Growth of sharp interfaces possible - therefore very suitable for heterostructures, e.g., multi quantum wells (MQW
35、) 2021/2/13 SaturdayTSSEL part-1-MOVPE growth.ppt - version 1.0Summary Discussed topics: Properties of commonly used precursors Fundamental MOVPE growth principles Devices made by MOVPE Dr. Walter Reichert AIXTRON A.G. & Trevor Webb THOMAS SWAN SCIENTIFIC EQUIPMENT LTD.2021/2/13 SaturdayTSSEL part-1
36、-MOVPE growth.ppt - version 1.0TSSEL 3X2” CCS InP MOCVD System2021/2/13 SaturdayTSSEL part-1-MOVPE growth.ppt - version 1.0源输送子系统源输送子系统 (Gas Delivery System)反应室与加热子系统（反应室与加热子系统（Reactor & Heater System）低压子系统低压子系统 (Low Pressure Exhaust System)尾气处理子系统尾气处理子系统 (Dry Scrubber System)安全与控制单元安全与控制单元 (Safety
37、& Control Unit)3X2” CCS InP MOCVD系统构成Key Laboratory of Optical Communication & Lightwave Technologies, Ministry of Education2021/2/13 SaturdayTSSEL part-1-MOVPE growth.ppt - version 1.0 AsH3TMGa - (CH3)3GaHCAsGaPrecursors MolecularsV 族源：族源：AsH3 PH3 NH3 III 族源：族源：TMAl TEAl TMGa TEGa TMIn TEIn掺杂源：掺杂源：
38、DMZn DEZn Cp2Mg CBr4 SiH4 Si2H6 H2S2021/2/13 SaturdayTSSEL part-1-MOVPE growth.ppt - version 1.0分子式分子式分子量分子量熔点熔点饱和蒸汽压公式饱和蒸汽压公式冷阱温冷阱温度度饱和蒸汽饱和蒸汽压压(CH3)3GaTMGa 114.82-15.8 C0 C68.480Torr(CH3)3AlTMAl 72.0915.4 C10 C4.832Torr(CH3)3In TMIn 159.9388.4 C25 C1.714Torr(C2H5)2Zn DEZn 123.49-28.0 C5 C4.989Torr1
39、703/T(K)-07.8P(mmHg)Log10 3204/T(K)-10.98P(mmHg)Log10 2135/T(K)-224. 8P(mmHg)Log10 2109/T(K)-8.28P(mmHg)Log10 金属有机源 (MO Source)2021/2/13 SaturdayTSSEL part-1-MOVPE growth.ppt - version 1.0Double Plenum Showerhead2021/2/13 SaturdayTSSEL part-1-MOVPE growth.ppt - version 1.0Closed Coupled ShowerheadNo
40、zzleOptical Port2021/2/13 SaturdayTSSEL part-1-MOVPE growth.ppt - version 1.0ReactorGraphiteSusceptor SusceptorSupportLower Quartz Liner2021/2/13 SaturdayTSSEL part-1-MOVPE growth.ppt - version 1.0Graphite HeaterZone AZone BZone CInP系统采用石墨加热器，系统采用石墨加热器，GaN系统采用钨丝加热器系统采用钨丝加热器2021/2/13 SaturdayTSSEL pa
41、rt-1-MOVPE growth.ppt - version 1.0Thomas Swan Scrubber SystemsEpisorb AsH3 & PH3 EpiCat NH3 2021/2/13 SaturdayTSSEL part-1-MOVPE growth.ppt - version 1.0Basic PrinciplesEpiSorb II (2 columns)Two- column design permits simultaneous adsorption in one column and oxidation in the other. Adsorption onto Charcoal mediumOxidation of other column5 programmable Oxidation steps
