Crystal Growth Laboratory€¦ · crystal growth equipment and processes together with its industrial partners. The Crystal Growth Laboratory is currently actively working in the

Crystal Growth LaboratoryYour Competent Partner

in Crystal Growth andSolidification Processes

Annual Report 2000

- Equipment and Process Development -- Optical and Electrical Characterisation -

- Numerical Modelling -

Universität Erlangen-Nürnberg

Structure

Process Development 3" and 4" GaAsB. Birkmann, L. Kowalski

Process Development 2" InPU. Sahr

Low Defect III-V SemiconductorsB. Birkmann WW6

Heat TransportO. Gräbner

Oxygen TransportA. Mühe

300mm Technology of Czochralski SiliconProf. Dr. G. Müller IIS-B

Process Development CaF2 Process Simulation CaF2

Optical materials for the 157nm TechnologyDr. J. Friedrich IIS-B

Layer Deposition, EpitaxyP. Berwian, M. Purwins

CharacterisationC. Hack

Thin Film Solar CellsP. Berwian WW6

Global Thermal SimulationT. Jung, M. Krause, B. Fischer

Radiation, TrainingG. Ardelean

Convection 2D/3DM. Hainke, D. Vizman

Point Defects, DislocationsM. Krause, D. Vizman

Magnetic Field Effects, Mass TransportB. Fischer, D. Vizman

High Performance ComputingB. Fischer

Grain Structure in Alloy SolidificationR. Backofen

User InterfaceF. Jurma

Numerical Modelling (codes: STHAMAS, CrysVUN) Dr. J. Friedrich IIS-B

Crystal Growth LaboratoryHead: Prof. Dr. G. MüllerRepresentative: Dr. J. FriedrichSecretary: G. Polepil

Structure

Crystal Growth Laboratory

General MaterialPropertiesMaterial Science andTechnology of MetalsGlass and Ceramics

Corrosion Scienceand Surface TechnologyPolymer Materials

Micro Characterisation

Electrical EngineeringMaterials

Department of MaterialScience and Engineering

Technical Faculty

Friedrich AlexanderUniversity

SemiconductorManufacturingTools and MaterialsTechnologySimulation

Technology

Power Electronicand Power DevicesCrystal Growth

Device TechnologyDivision

Fraunhofer Institute ofIntegrated Circuits

FraunhoferSociety

Staff

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Address:Crystal GrowthLaboratoryMartensstr. 7,91058 Erlangen

Name

Fax:+49-9131-8528495

Tel. +49-9131- EmailGheorghe Ardelean 761-252 [email protected] Backofen 761-135 [email protected] Berwian 852-7757 [email protected] Birkmann 852-7722 [email protected] Fischer 761-231 [email protected]. Jochen Friedrich 761-344 [email protected] Gräbner 761-333 [email protected] Hack 852-7757 [email protected] Hainke 761-136 [email protected] Hilburger 761-226 [email protected] Jurma 761-136 [email protected] Kowalski 852-7720 [email protected] Krause 761-251 [email protected] Molchanov 761-225 [email protected] Mühe 761-332 [email protected]. Dr. Georg Müller 852-7636 [email protected] Polepil 852-7729 [email protected] Purwins 852-7757 [email protected] Sahr 852-7722 [email protected]. Daniel Vizman 761-229 [email protected]

Staff

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Overview

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The Crystal Growth Laboratory(CGL) develops and optimizesequipment and processes forthe bulk growth ofsemiconductor and fluoridecrystals as well as for the thinfilm deposition. The CrystalGrowth Laboratory is providedwith user friendly simulationprograms, which are especiallysuitable for the calculation ofthe global heat and masstransport in high temperatureequipment with complexgeometry. These computercodes are continuously furtherdeveloped in close co-operationto the industrial users withregard to new or improvedphysical models, to an easierway to use the programs andto more efficient algorithms. Inaddition they are used for andby the industrial partner todevelop crystal growthequipment and processes. TheCrystal Growth Laboratory isacknowledged for its activitieswith respect to thedevelopment and use ofmeasuring techniques fordetermining the mass and heattransport in crystal growthprocesses as well as forthermodynamic and kineticstudies during layer deposition.In addition numerous methodsfor electrical and opticalcharacterization of crystals areavailable.

Crystal growth is one keytechnology in the chain of allmanufacturing processes forelectronic and opto-electronicdevices. There is a continuousdemand on the increase of the

quality of the substrates withrespect to geometricaldimensions, purity,crystallographic perfection andhomogeneity of the electricaland optical properties.Therefore, the topics of theCrystal Growth Laboratory dealwith the development andoptimization of advancedcrystal growth equipment andprocesses together with itsindustrial partners. The CrystalGrowth Laboratory is currentlyactively working in the field ofsemiconductor materials like Si,GaAs, InP and optical materialslike fluoride and oxide crystalsas well as with materials forsolar cells. Meanwhile, theCrystal Growth Laboratory hasexpanded the use of itsknowledge in numericalsimulation and solidificationphenomena to other processesof technical relevance likecasting of metallic alloys, too.

The Crystal Growth Laboratorywas founded at theDepartment of MaterialsScience by Prof. Dr. GeorgMüller in 1979. Since 1996 theCrystal Growth Laboratory hasestablished the working group"crystal growth" at theFraunhofer Institute forElectronic Devices (headProf.Ryssel) in Erlangen. Thisworking group became theDepartment Crystal Growth inautumn 1999. Since thefoundation of the CrystalGrowth Laboratory 100"Study" theses, 70 Mastertheses and 27 Ph.D. theses,contributing to the research

work of the crystal growthlaboratory have been published.More than 90% of funding ofthe Crystal Growth Laboratoryresults from research contractsdirectly with industrial partnersand with the German Ministryfor Research and Development,the Bavarian ResearchFoundation, the BavarianGovernment, the GermanResearch Foundation (DFG).

In 2000 the highlights of theCrystal Growth Laboratory canbe summarized as follows:• 3” GaAs single crystals have

been grown by the VGFtechnique with a dislocationdensity below 30cm-2. Inaddition 2” InP singlecrystal has been producedhaving an EPD of less than2000cm-2. Both values areat least national records.

• A new furnace for thegrowth of CaF2 – crystalswhich was completelydeveloped and constructedby the Crystal GrowthLaboratory was successfullycommissioned and a firstsingle crystal was grown. Inparallel the industrialpartner Schott ML hasopened the biggest fab forthe production of fluoridecrystals. The furnaces insidethe fab have beenconstructed with thenumerical support of theCrystal Growth Laboratory.

• Further examples for thecompetence of the CrystalGrowth Laboratory innumerical simulation is the

Overview

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fact, that FreibergerCompound Materials (FCM)have moved its VGF processfrom the developmentstatus to production.Furthermore, FCM hasbecome world marketleader in 6” substrates. TheCrystal Growth Laboratoryhas supported FCM by itsmodeling experience andsoftware tools.

• The Super Silicon ResearchInstitute has given theCrystal Growth Laboratorya 400mm Silicon wafer inreturn for the reliability ofits software tools deliveredto Super Silicon for the lasttwo years.

• Several new projects havebeen launched in 2000.Among others, one project,together with SiemensSolar, is on the globalthermal modeling of the so-called TRI-SI Czochralskiprocess for the productionof solar cell material. TheCrystal Growth Laboratoryhas also continued itstradition in microgravityresearch and initiatedprojects on the utilization ofthe International SpaceStation.

The Crystal Growth Laboratorymaintains national but alsointernational co-operations toindustry. In 2000 the industrial

partners are Wacker Siltronic(D), Freiberger CompoundMaterials (D), Schott ML (D),Siemens Solar (D), Linn HighTherm (D), Riedhammer (D),KSB (D), MEMC (I), MitsubishiElectrics (JP),Wafertechnology(UK), Super Silicon (JP), LGSiltron (KO), Sumitomo Electrics(JP), MA/COM (USA).

Crystal Growth Laboratory - Partners

• ACCESS, Aachen• Bergakademie, Freiberg• CAESAR, Bonn• DLR, Köln• Forschungszentrum Rossendorf,

Dresden• Institut für Kristallzüchtung, Berlin• Phys. Institut, Uni Stuttgart

GermanyGermanyGermanyGermany• EFU,EFU,EFU,EFU, Simmerath Simmerath Simmerath Simmerath• FreibergerFreibergerFreibergerFreiberger Compound Materials, Compound Materials, Compound Materials, Compound Materials,

FreibergFreibergFreibergFreiberg• I&P,I&P,I&P,I&P, Herzogenrath Herzogenrath Herzogenrath Herzogenrath• LinnLinnLinnLinn High High High High Therm Therm Therm Therm,,,, Eschenfelden Eschenfelden Eschenfelden Eschenfelden• Schott GlasSchott GlasSchott GlasSchott Glas, Mainz, Mainz, Mainz, Mainz• SchottSchottSchottSchott ML, ML, ML, ML, Jena Jena Jena Jena• SiemensSiemensSiemensSiemens Solar, Solar, Solar, Solar, München München München München• TitalTitalTitalTital,,,, Bestwig Bestwig Bestwig Bestwig• VAW, BonnVAW, BonnVAW, BonnVAW, Bonn• Wacker SiltronicWacker SiltronicWacker SiltronicWacker Siltronic,,,, Burghausen Burghausen Burghausen Burghausen

EuropeEuropeEuropeEurope• AlcanAlcanAlcanAlcan, United Kingdom, United Kingdom, United Kingdom, United Kingdom• CorusCorusCorusCorus, United Kingdom, United Kingdom, United Kingdom, United Kingdom• CEA, France• MADYLAM, France• MEMC, ItalyMEMC, ItalyMEMC, ItalyMEMC, Italy• Soreq Soreq Soreq Soreq NRC, NRC, NRC, NRC, IsrealIsrealIsrealIsreal• Wafer Technology, United KingdomWafer Technology, United KingdomWafer Technology, United KingdomWafer Technology, United Kingdom• Uni. Sheffield, United Kingdom• Uni. Miskoloc, Hungary• Uni. Timisoara, Romania

Asia/USAAsia/USAAsia/USAAsia/USA• LGLGLGLG Siltron Siltron Siltron Siltron, Korea, Korea, Korea, Korea• MA/COM, USAMA/COM, USAMA/COM, USAMA/COM, USA• MitsubishiMitsubishiMitsubishiMitsubishi Electrics Electrics Electrics Electrics, Japan, Japan, Japan, Japan• Super Silicon, JapanSuper Silicon, JapanSuper Silicon, JapanSuper Silicon, Japan• SumitomoSumitomoSumitomoSumitomo Electrics Electrics Electrics Electrics, Japan, Japan, Japan, Japan• Uni. Minnesota, USA• Uni. Stony Brook, USA

Current partners of the Crystal Growth Laboratory

Low Defect GaAs SemiconductorSubstrates by the VGF - Technique

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Nowadays there is a greatdemand for III/V-semiconductors due to thegrowing markets of highfrequency electronics (formobile telephones) andoptoelectronic devices. Thelatter include high brightnesslight emitting diodes and diodelasers. It is expected thatconventional lamps will soon bereplaced in many fields ofapplications by light emittingdiodes due to their lowerconsumption of energy. Thesame applies for lasers: Thereare plans to partially replacesolid state lasers forapplications like welding andcutting by semiconductorlasers, or at least to use diodelasers for optical pumping ofsolid state lasers. Because of the high current andpower densities in the activezones of these devices crystaldefects in the substrates e.g.dislocations lead to a rapiddevice degradation. Thereforesingle crystals with a low defectdensity and a highhomogeneity are required. Inthe case of Gallium Arsenide(GaAs) a typical upper limit forthe dislocation density, which ismeasured in terms of the etchpit density (EPD), is 500 cm-2.Additionally a charge carrierdensity (n) of 0,8⋅1018 - 3,0⋅1018

cm-3 is necessary to enable thesubstrate to carry currentdensities in the order of somekA/cm-2.

As the standard growthtechnique for III/V-materials, theliquid encapsulated Czochralski(LEC) technique, is not able toprovide crystals which fulfill therequirements mentioned above,a new growth technique(Vertical Gradient Freeze, VGF)was developed within the lastdecade. At present this growthtechnique is in the transitionfrom development toproduction stage in theindustry. The crystal growthlaboratory contributed to theVGF-technique from laboratoryup to the production stage. In the VGF-technique thepolycrystalline raw material ismolten in a crucible. After themelting process the material isdirectionally solidified from asingle-crystalline seed at thebottom of the crucible. This isachieved by lowering thetemperature while maintaining

a positive temperature gradientin the melt. As the crystalgrowth is usually performed inmultizone furnaces there aremany degrees of freedom.Therefore, numerical modelingis applied for the optimizationof the furnaces and the growthprocesses. In the last year there wereextensive studies in order tooptimize the crucible supportsfor our furnaces. As a result theEPD of crystals with 3 inchdiameter decreased to valuesbelow 100 cm-2 in the wholecrystal. On wafers close to theseed a EPD of 30 cm-2 could bereached. This EPD is far belowthe values specified above. Atypical 3” crystal has a lengthof 10 cm in the cylindrical part.The weight is about 3 kg. In 2000 it was also possible toreproduce the growth of a 4

4” GaAs single crystal grown at CGL by the VGF method

Low Defect GaAs SemiconductorSubstrates by the VGF - Technique

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inch single crystal. The 4 inchcrystals now fulfill thespecifications for the chargecarrier concentration of lasermaterial. Further work has tobe done on lowering the EPDfor these large diametercrystals. Due to the increase indiameter and length (13 cm)these crystal weight 7 kg andmore.

Recent PublicationsB. Birkmann, M. Rasp, J.Stenzenberger, G. MüllerGrowth of 3" and 4" galliumarsenide crystals by the verticalgradient freeze (VGF) methodJ. Cryst. Growth 211 (2000)157-162

R. Backofen, M. Kurz, G. MüllerProcess Modelling of theIndustrial VGF Crystal GrowthProcess Using the SoftwarePackage CrysVUN++J. Cryst. Growth 211, (2000)202-206

M. Kurz, G. MüllerControl of Thermal Conditionsduring Crystal Growth byInverse Modelling

J. Cryst. Growth, 208, (2000)341-349

M. Metzger, R. Backofen,Optimal temperature profilesfor annealing of GaAs-CrystalsJournal of Crystal Growth220,(2000) 6-15

J. Amon, J. Härtwig, W.Ludwig, G. Müller, Analysis ofTypes of Residual Dislocationsin the VGF Growth of GaAswith extremely low DislocationDensity (EPD << 1000cm-2), J.Crystal Growth, (1999) 367-373.

J. Amon, P. Berwian, G. Müller,Computer-Assisted Growth ofLow-EPD GaAs with 3''Diameter by the VerticalGradient-Freeze Technique, J.Crystal Growth 198/199, (1999)361-366

G. Müller, Melt Growth ofSemiconductors, Materials-Science-Forum.vol.276-277;1998; p.87-108.

J. Amon, F. Dumke, G. Müller,Influence of the crucible shapeon the formation of facets andtwins in the growth of GaAs bythe vertical gradient freezetechnique J. Crystal Growth187, (1998) 1

ContactBernhard Birkmann

EPD Mapping of a 3” GaAs single crystal grown at CGL by the VGFmethod. The mean EPD value is only 31cm-2

Low Defect InP SemiconductorSubstrates by the VGF - Technique

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Indium phosphide is a III-Vcompound semiconductor crys-tallizing in the sphalerite struc-ture, which has a fortuitous lat-tice match to alloys with band-gaps coinciding with the 1.3and 1.55 µm windows in opti-cal fiber. The revolution in opti-cal fiber communications hasswept InP into a dominant posi-tion in optoelectronics. For lat-tice-matched growth of ternaryalloys InGaAs and InAlAs andquarternary InGaAsP and AlIn-GaAs, InP is the substrate ofchoice. Heterostructure devicesbased on these alloys, by virtueof their bandgaps, provide astrong driving force for bulk InPcrystal growth development.

During the past twenty-fiveyears, as the growth of InP sin-gle crystals has gone from alaboratory curiosity to a com-mercial process, many new ap-plications for InP substrateshave emerged. The mainstay ofdemand continues to be in thefield of telecommunications,but other uses for InP materialinvolving high speed electronicand photonic circuits have ar-rived. In addition to high fre-quency wireless communica-tions, broadband gigahertz ra-dar has been achieved using InPphotoconducting antennas.

The state of the art today forInP crystal growth is dividedbetween two competingtechnologies; liquidencapsulated crystal pulling(LEC) with top seeding, andvertical growth in a container(VGF, VB) with bottom seeding.

The pulling method hasgenerally been the most costeffective, but its disadvantage isthe high dislocation densitycaused by high levels of strainduring growth. On the otherhand, vertical container growthoffers a very low dislocationdensity because of its low-stressenvironment. But it is plaguedby yield problems due totwinning and interfacebreakdown in heavily dopedcrystals.

Since 1992 the crystal growthof InP by the VGF-technique isdeveloped. In 1996 the firstsingle crystal in Europe wasgrown by D. Zemke at the CGL(Crystal Growth Laboratory).Since 1998 the crystal growthprocess is a "semi-open" proc-ess, i.e. the InP is fully encap-sulated by a liquid B2O3-film;the crucible with melt and crys-tal is placed in a closed silica

ampoule, but the ampoule hasa small gap at the cold side ofthe furnace to allow for a pres-sure balance and condensationof excess phosphorus. To avoidtwinning, the main problemduring the crystal growth proc-ess, a so called flat bottom cru-cible is used. The advantage ofreducing the dislocation densityby diameter expansion in theconical part is lost in this ar-rangement. Consequently,conditions of low thermal stressduring the seeding process arerequired.

InP crystals were grown in<100>-direction. The seedsused, up to now, were grownby the LEC-method. The EPDvaried between 3·104 cm-2 and5·104 cm-2. The seeding iscontrolled usingthermocouples.

2” InP single crystal grown at CGL by the VGF method.

Low Defect InP SemiconductorSubstrates by the VGF - Technique

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In 2000 with the VGF-furnaceset-up a single crystal with 2”diameter and a length of 9 cmwas grown. The weight isabout 1 kg. The carrierconcentration varied between3-8·1017 cm-3. The material fromthe crystals is sliced to (100)-wafers. The slices are etchedwith the Huber etchant and theetch-pit-density is below 1800cm-2.

The VGF-furnace was designedby the aid of numericalsimulation. Using the computercode CrysVUn++ (developed atthe CGL), quasi-stationary andtime-dependent simulations canbe performed. First thetemperature distribution in thefurnace is modeled. Theposition and the shape of thesolid liquid interface aredetermined at various timesteps during the crystal growthprocess. To reach conditions oflow thermal stress the stressdistribution is also calculatedwith CrysVUn++. Furthermoretemperature fluctuations duringthe crystal growth process canbe calculated by time-dependent simulations.

Recent PublicationsR. Backofen, M. Kurz, G. MüllerProcess Modelling of theIndustrial VGF Crystal GrowthProcess Using the SoftwarePackage CrysVUN++J. Cryst. Growth 211, (2000)202-206

M. Kurz, G. MüllerControl of Thermal Conditionsduring Crystal Growth byInverse ModellingJ. Cryst. Growth, 208, (2000)341-349

M. Metzger, R. Backofen,Optimal temperature profilesfor annealing of GaAs-CrystalsJournal of Crystal Growth220,(2000) 6-15

G. Müller, Melt Growth ofSemiconductors, Materials-Science-Forum.vol.276-277;1998; p.87-108.

ContactUwe Sahr

EPD Mapping of a 2” InP single crystal grown at CGL by the VGFmethod. The mean EPD value is only 1500cm-2

300mm Silicon CzochralskiCrystal Growth

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In Silicon Czochralski crystalgrowth the R&D activities aremotivated by the aim to growdislocation free crystals of 300mm in diameter and larger. Thisincrease of the crystal diameterresults in an increase of themelt volumes in order to in-crease the yield and to decreasethe costs. The increase of theneeded crucible dimensionscauses the melt flow driven bylarge temperature gradients tobe three-dimensional, time-dependent and turbulent whichin most cases has a detrimentaleffect on the heat- and mass-transfer and thereby on thecrystal quality.

The prediction of melt-flows incrucibles with diameters of upto 1 m and melt charges of upto 500 kg by numerical simula-tion would be a solution sinceimproved furnace parameterscould then be found by nu-merical experiments. However,a realistic simulation of the flowin such large melts is only partlypossible at the moment even byusing high performance com-puting. For that reason, theheat- and mass-transfer in suchmelts still has to be investigatedexperimentally using appropri-ate sensor equipment. Thereby,the influence of process pa-rameters like crystal- and cruci-ble-rotation, inert gas flow andpressure, hot zone design andmagnetic field configurationson the transport processes is ofspecial interest.

For in-situ analysis oftemperature distributions in the

production facilities of itsindustrial partner WackerSiltronic AG the Crystal GrowthLaboratory has developedappropriate measurementequipment. Temperaturedistributions within the whole

silicon melt as well as localtemperature fluctuations aremeasured during crystal growthusing mobile thermocouplearrangements and fibre-opticaltemperature sensors madefrom sapphire or quartz glass.

The measured data areprimarily used to select processparameters, which are suitableto improve significantly theheat and mass transportconditions. Furthermore, theyare used to provide benchmarkdata for the development andverification of numericalmodels. Thereby, it was foundthat only optical measurementof the temperature fluctuationsreveal the full information onthe degree of turbulence of the

melt flow due to the fact thattemperature signals obtainedfrom thermocouples arestrongly damped in the higherfrequency range.

In addition to the temperature

distribution the transport ofoxygen plays an important rolein the Czochralski growth ofsilicon crystals. The oxygenenters the silicon melt due tothe dissolution of the silicacrucible. In order to measurethe dissolution rate of the silicacrucible as a function oftemperature and gas pressurean in-situ measuring techniquebased on the measurement ofreflection was developed. Theseexperimental results serve asinput data for numericalsimulation.

Up to now, the investigation ofthe correlation between thegrowth parameters and theoxygen transport was onlypossible ex-situ by analysing the

Arrangement of measuring positions for the determination of thetemperature distributions in Si melts

300mm Silicon CzochralskiCrystal Growth

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grown crystals. Therefore, theCrystal Growth Laboratory hasdeveloped an oxygen sensor forin-situ measurement of theoxygen concentration in themelt as well as in the gas phaseduring crystal growth. Theoxygen concentration in the gasis related to the concentrationin the melt. Thus, this valuecould be used for an activecontrol of the oxygenconcentration in the crystal.Currently, the sensors areapplied successfully todetermine the influence of thedifferent process parameters onthe oxygen transport.

Recent Publications

J. Friedrich, B. Fischer, O.Gräbner, D. Vizman, G. MüllerHigh performance computingfor the analysis of the influenceof steady magnetic fields onconvective heat transfer inCzochralski melts: comparisonto experimental resultsProc. 4th Int. PAMIRConference, Presqu`ile deGiens, France (2000) 239-244

A. Mühe, R. Backofen, J.Fainberg, G. Müller, E.Dornberger, E. Tomzig, W. v.Ammon, Oxygen Distribution inSilicon Melt During a StandardCzochralski Process Studied bySensor Measurements andComparison to NumericalSimulation, J. Crystal Growth198/199 (1999)

G. Müller, A. Mühe, R.Backofen, E. Tomzig, W. v.Ammon, Study of Oxygentransport in Cz growth ofsilicon, MicroelectronicsEngineering 1, (1999) 135-147

A. Seidl, G. Müller, E.Dornberger, E. Tomzig, B.Rexer, W. v. Ammon, Turbulentmelt convection and itsimplication on large diametersilicon Czochralski crystalgrowth, Proceedings of theEighth International Symposiumon Silicon Materials Science and

Technology. Silicon MaterialsScience and Technology.Electrochem. Soc, Pennington,NJ, USA (1998) 417-428 .

ContactOliver Gräbner

Temperature distributions in a Si – Cz- melt for crucible rotation rates1rpm, 2rpm and 5 rpm

Growth of CaF2 Crystals asLenses for the DUV Lithography

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Photolithography is a keytechnology for the productionof semiconductor devices. Thepreceding reduction of thefeature size of devices implies areduction of the opticalwavelength into the ultraviolet

range and thus the need fornew suitable materials for theoptical components. Presentprojection systems which canbe used at wavelengths downto 248 nm are using fused silicacomponents. The nextgeneration of wafer stepperswill be operating atwavelengths of 193 nm andlater 157 nm, where fused silicacannot be used any morebecause of the high absorptionlosses.

Single crystalline CaF2 hasexcellent transmissioncharacteristics down to deepUV and is therefore selected asthe main optical material forthe next generation of

lithography. The materialrequirements for this opticalapplication are extremely high.Thus, single crystals of CaF2

with low defect density andextremely high uniformity areneeded. Apart from impurities,all types of crystal defects, i.e.dislocations, play a major roleconcerning the optical qualityof the crystals. Therefore it isimportant that the thermalstress during crystal growth isminimized.

Thereby, numerical simulationplays an important role toidentify the adequate growthsetup and to optimize theprocessing conditions. Withrespect to this the Crystal

Growth Laboratory uses itsexperience in the field ofnumerical simulation of heattransport processes and itsknow-how of development ofcrystal growth process tosupport the equipment andprocess development of itsindustrial partner Schott ML.

The Crystal Growth Laboratorytogether with its industrialpartner has optimized thethermal set-up of the

Planned development of the feature size and the used exposure wave lenghts (Source: Schott ML)

Growth of CaF2 Crystals asLenses for the DUV Lithography

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production facilities. Inaddition, the Crystal GrowthLaboratory analyzes andevaluates by computersimulation different processstrategies for its industrialpartner in order to achievehigher yield and materialquality.

Beside numerous numericalsimulation the Crystal GrowthLaboratory has also developedand built an especially designedR&D-furnace for the growth ofCaF2 crystals, which is equippedwith a variety of in-situmeasurement systems to obtaininformation about temperaturedistributions in the crystal/meltsystem as well as data aboutchemical reaction taking placeduring processing.

Already in the first crystalgrowth run a single crystal hasbeen grown in this R&D facility.In addition experimental datahave been made availablewhich serve as benchmark datafor the numerical simulationand are also valuable for theprocess used by the industrialpartner. Based on these data itis confirmed that an importantissue is the properconsideration of the internalheat transfer by radiationduring crystal growth in thesemitransparent CaF2.

First CaF2 crystal grown in the new R&D furnace developed by CGL

Chalcopyrite SemiconductorsFor Thin Film Solar Cells

11.07.03

Chalcopyrite semiconductorsare promising absorbermaterials for thin film solar cellapplications due to their highabsorption coefficient. Themost important compound isCuInSe2 (commonly abbreviatedas CIS) with a band gap of 1.0eV. By alloying CIS with otherchalcopyrites e.g. CuInS2 (bandgap 1.5 eV) or CuGaSe2 (bandgap 1.7 eV) it is possible totailor band gap and cell voltagecorresponding to therequirements of modulefabrication. In Germany thestate of the art in CIS solar celldevelopment is the installationof two pilot manufacturingfacilities for the production ofmodules with monolithicallyintegrated cells.

CGL is working in differentprojects with the financialsupport of the DFG and theBavarian Research Fundationand in cooperation withSiemens AG/Siemens SolarGmbH on the following topics:

The optical and electrical prop-erties of CIS are strongly af-fected by intrinsic defects. Inorder to investigate the correla-tion of stoichiometry deviationand semiconducting propertieswithout the influence of grainboundaries single crystalgrowth experiments are per-formed using solution growthtechniques such as SolutionBridgman and Travelling HeaterMethod. Therefore, it is neces-sary to study the phase rela-tions between CuInSe2 and thedifferent solvents. Using Indium

or binary compounds like CuSeand InSe as solutes it was pos-sible to prepare CIS-sampleswith different lattice parame-ters, conductivity types andvarying intrinsic defect popula-tion.

The morphology of evaporatedCIS-films grown on bulk sub-strates and their correspondingproperties are investigated. Theinfluential parameters for thestudy are the Cu/In- and theSe/metal-ratio, the sequence ofthe elemental layers and thetemperature-time-program. Forthe different processes using ei-ther pure metal or Se-containing precursors an ap-propriate chemical surfacetreatment of the substrates isadvantageous to achieve nu-cleation of the CuInSe2-film.

The formation of polycrystallineCIGS films during selenizationof metallic precursors is ob-served in-situ by Thin Film Calo-rimetry (TFC). At first the im-portant binary reactions in the

Cu-In, In-Se and Cu-Se systemswere analysed by TFC and ex-situ X-Ray Diffraction. Untilnow a model for the reactionpath for composing the ternaryCuInSe2-phase from the precur-sors was established. In the fu-ture the influence of Ga and Naon the formation of the Cu-InSe2-film will be investigated.In future an optimised tempera-ture-time program should bedeveloped using in addition in-situ X-ray-diffraction (co-operation with the Institute ofCrystallography and StructuralPhysics, Prof. Magerl, FAU Er-langen-Nürnberg).

Recent PublicationsB. Eisener, D. Wolf, G. MüllerElectrical properties of mixedphase CuInSe2-Cu2In4Se7 bulkcrystalsJap. J. Appl. Phys., (2000)(submitted)B. Eisener, D. Wolf, G. MüllerPhase relations in the TernaryCu-In-Se System concerning theTriangle CuInSe2-InSe-In2Se3

CuInSe2 bulk crystal grown from an In solution

Chalcopyrite SemiconductorsFor Thin Film Solar Cells

11.07.03

12th International Conference ofTernary and MultinaryCompounds, Taiwan, March2000, submitted

D. Wolf, G. MüllerIn-situ Monitoring of PhaseFormation in CuInSe2 Thin Films12th International Conference ofTernary and MultinaryCompounds, Taiwan, March2000, submitted

P. Berwian, D. Wolf, G. Müller,W. Stetter, F. KargInvestigation of phaseformation in the Cu-In-Ga-Sesystem by thin film calorimetryand x-ray diffraction16th European Conf. onPhotovolt. Sol. Energy Conv.,Glasgow, UK, 2000, submitted

Ch. Hack, G. MüllerNucleation of CIS-thin films onmonocrystalline CIS-substrates16th European Conf. onPhotovolt. Sol. Energy Conv.,Glasgow, UK, 2000, submitted

M. Leicht, D. Stenkamp, H.P.Strunk, D. Wolf D., B. Eisener,G. Müller, Nanoscopiccrystallography of chalcopyriteCuInS2 by techniques ofconvergent-beam electrondiffraction, Phil Mag. A79,(1999) 1033-1043

B. Eisener, M. Wagner; D. Wolf,G. Müller, Study of the intrinsicdefects in solution grownCuInSe2 crystals depending onthe path of crystallization, J.

Crystal Growth 198/199, (1999)321-324

D. Wolf, G. Müller, In-situInvestigation of Cu-In-Se-Reactions by Thin-FilmCalorimetry, Thin-Film,Structures for Photovoltaics.Symp. Materials ResearchSociety, Warrendale, PA, USA(1998); 173-178.

D. Wolf, G. MüllerThin Film Calorimetry as a Toolfor in-situ Investigation ofReactions in the Cu-In-Seternary System, Ternary andMultinary Compounds.Proceedings of the 11th Int.Conf. on Ternary and MultinaryCompounds. ICTMC-11.Institute of Physics Publishing,Bristol, UK (1998) 281-284

Ch. Hack, D. Wolf, G. Müller,Liquid Phase Homoepitaxy ofCuInS2, Ternary and MultinaryCompounds. Proceedings ofthe 11th Int. Conf. on Ternaryand Multinary Compounds.

ICTMC-11. Institute of PhysicsPublishing, Bristol, UK (1998)285-288

B. Eisener, H. Kuhn, G.Drüsslein, D. Wolf, G.Müller,Solution growth of CuInSe2and CuInS2 bulk crystals andtheir characterization, Ternaryand Multinary Compounds.Proc. of the 11th Int. Conf. onTernary and MultinaryCompounds. ICTMC-11.Institute of Physics Publishing,Bristol, UK (1998) 131-134

ContactPatrick Berwian

nucleation layer of CuInSe2 grown by LPE on a CuInSe2 substrate

Modeling of Crystal Growth Processes

11.07.03

The tasks of the working group"Modeling of crystal growthand solidification processes"are the development and theuse of simulation programs forthe calculation of heat andmass transport in high tem-perature furnaces and relatedprocesses. This includes the useof modern numerical methodsin our software packages, thepreparation of user-friendlygraphical interfaces as a prem-ise for granting licenses, theimplementation of new physicalmodels as well as their verifica-tion by comparison to experi-mental results, and finally, theteaching and support of the li-censees.

In this context the CrystalGrowth Laboratory hasdeveloped two programpackages for the simulation oftwodimensional andaxisymmetric geometries:STHAMAS and CrysVUN. Theseprograms are based on thefinite volume method andnumerically solve the heat and

mass transport equations incomplex geometries, takinginto account heat conduction,laminar/turbulent convectionand radiation. Both programsallow the calculation ofdiffusive and convective speciestransport of e.g. oxygen insilicon melts or of dopants insemiconductor andmetallurgical melts. In addition,the programs are, among otherthings, able to treat thermalstress and different kinds oftime-dependent and stationarymagnetic fields. While CrysVUNuses unstructured grids,STHAMAS works with block-structured grids. Both possessa graphical user interface,which ensures an easy use ofthe programs. CrysVUN andSTHAMAS are used inside CGLfor ordered simulations and forthe support of our ownexperimental working groups,but also by external users vialicenses. The followingcompanies and institutesbelong to the softwarecustomers of the Crystal

Growth Laboratory: FreibergerCompound Materials, SchottGlas/ML, Super Silicon, LGSiltron, M/A-COM, MitsubishiElectrics, Linn High Therm,Riedhammer, SumitomoElectrics, MEMC, WaferTechnology, Soreq NRC,Siemens Solar, IKZ Berlin, FZRossendorf, CAESAR, DLR,University of Stuttgart.

Compared to other commercialsoftware, the advantage ofCrysVUN and STHAMAS lies inthe fact that they have beendeveloped especially for crystalgrowth, and that they havebeen verified experimentally. Inaddition, CrysVUN is designedfor the solution of inverseproblems. This e.g. allows thedetermination of optimal heaterpowers for a desired temporaland spatial temperaturedistribution (see also annualreport 1999).

Moreover, the possibility ofdefect engineering is currentlyadded to the programs.

Without fieldωx = -20rpm, ωc = 2rpm

Measured (left) and with STHAMAS3D calculated (right) temperature distribution in a vertical cross section in a SiCzochrlaski melt with 14“ diameter

Modeling of Crystal Growth Processes

11.07.03

For example, this includes thecalculation of point defects likevacancies and interstitials beinggenerated during the growth ofsilicon by the Czochralskimethod (see also annual report1999). Both CrysVUN andSTHAMAS offer the possibilityfor the calculation of radiativeheat transport in semi-

transparent media. In crystalgrowth equipments, these arethe crystals or the boron oxideused to cover the melt.

In addition, the Crystal GrowthLaboratory develops and usesthe finite volume codeSTHAMAS3D, which is basedon block-structured grids, forthe simulation of three-dimensional geometries. Anexample for this is thesimulation of complex flowphenomena in semiconductormelts during crystal growth bythe Czochralski method.Thereby, the melt is subjectedto different influences likecrystal and crucible rotation,magnetic fields, and especiallystrong buoyant forces. For thenumerical treatment of theresulting flow structures, a veryhigh spatial and temporalresolution is necessary.Therefore, STHAMAS3D ismainly used on highperformance computers. Forthe extension of thecalculations to the crystal-meltsystem, a model for thetreatment of the phaseboundary crystal-melt iscurrently implemented.

Recent PublicationsD.Vizman, B. Fischer, J.Friedrich, G. Müller3D numerical simulation of meltflow in the presence of arotating magnetic fieldInt. J. Num. Meth. Heat FluidFlow 10, (2000) 366

R. Backofen, M. Kurz, G. MüllerProcess Modelling of theIndustrial VGF Crystal GrowthProcess Using the SoftwarePackage CrysVUN++J. Cryst. Growth 211, (2000)202-206

M. Kurz, G. MüllerControl of Thermal Conditionsduring Crystal Growth byInverse ModellingJ. Cryst. Growth, 208, (2000)341-349

M. Metzger, R. Backofen,Optimal temperature profilesfor annealing of GaAs-CrystalsJournal of Crystal Growth220,(2000) 6-15

Ch. Frank, K. Jacob, M.Neubert, P. Rudolph, J.Fainberg, G. MüllerTemperature field simulationand correlation to the structuralquality of semi-insulating GaAscrystals grown by the vapourpressure controlled Czochralskimethod (VCz)J. Cryst. Growth 213, (2000)10-18

A. Voigt, M. MetzgerNumerical Simulation andControl of Industrial CrystalGrowth by the Czochralski andVertical Gradient FreezeMethodcaesar preprint 2000-2, (2000)

ContactJochen Friedrich

Crystal

Melt

Complex Geometry of a crystalgrowth facility with structured gridof STHAMAS (left) andunstructured grid of CrysVUN(right)

Support of Microgravity Experimentationby Using Numerical Simulation

11.07.03

Within living memory the art ofcasting is known. However, it isstill impossible to predict accu-rately the properties of the castproduct. In spite of increasingcomputing capacities the plu-rality of numerous processesoccurring on different lengthscales prevent an exact numeri-cal simulation on the micro-scopic scale. In alloys the fluidand solid phase can coexist in awide temperature range in op-posite to pure materials.Thereby, complex microstruc-tures result which determinethe final macroscopic propertiesof the cast product. Therefore,in material science experimentsin a microgravity environmentare carried out since a longtime in order to get an betterunderstanding of the formationof the microstructure in alloys.The special conditions undermicrogravity help to simplify thecomplexity of the processes oc-curring during solidification andallow therefore to study the in-fluence of certain parameters inmore detail.

The Crystal Growth Laboratoryis principal investigator of anEuropean compound project, inwhich the International SpaceStation Alpha (ISS) will be usedfor solidification experiments.The project is entitled "Micro-structure Formation in Castingof Technical Alloys under Diffu-sive and Magnetically Con-trolled Convective Conditions"(MICAST). Six European re-search institutes and 8 compa-nies participate in MICAST. Inspite of the non-usual research

platform the objective ofMICAST is also to contribute tosolve industrial problems. Theindustrial relevance of the proj-ect is obvious from the largenumber of industrial partici-pants. MICAST delas with Al-Sialloys, like AlSiMg or AlSiFe,which are the bedrock of thealuminium industry, i.e. in billetor slab casting and in shapedcasting like investment or sandcasting.

The non-everyday field of mi-crogravity research has a longtradition in the Crystal GrowthLaboratory. In the 80ies and90ies problems related to solidi-fication of materials have beeninvestigated by the head of theCrystal Growth Laboratory,Prof. Müller, in the GermanSpacelab Missions D1 and D2as well as during severalsounding rocket flights.

The aim of MICAST is to studyexperimentally as well numeri-cally microstructure formationduring casting of technical al-

loys under diffusive and mag-netically controlled convectiveconditions. Diffusive heat andmass transport conditions andprecisely controlled flow will beachieved by applying time-dependent magnetic fields in amicrogravity environment.

An important task for the Crys-tal Growth Laboratory is thesupport of the experimentalistby numerical simulation. Thefurnace ARTEMIS, developed bythe DLR, may serve as an ex-ample. An important construc-tive element of this furnace isthe use of an aerogel as mate-rial for the crucible. The ex-traordinary material is charac-terized by an extreme low valueof the thermal conductivitywhich is e.g. 3 orders of magni-tude smaller than silica. Be-cause of the transparency ofthe aerogel the solidificationprocess can be monitored opti-cally by using a CCD camerawithout disturbing the processitself. The numerical resultshave shown that it is necessary

Structure of the MICAST project

Support of Microgravity Experimentationby Using Numerical Simulation

11.07.03

to treat this material as semi-transparent in order to repro-duce correctly the thermal be-havior of the furnace.

In the frame of the project theCrystal Growth Laboratory willfurther develop the numericalmodel and adapt to the specialexperimental conditions. Onetask will be to implement aproper model for the descrip-tion of convection in the twophase region between solid andliquid phase. The model shouldbe validated by model experi-ments carried out by otherMICAST partners.

Recent PublicationsJ. Friedrich, R. Backofen, G.MüllerNumerical simulation of grainstructure and global heattransport during solidificationof technical alloys in MSLinserts under diffusiveconditionsCOSPAR 2000, Warsaw, July17-19 2000, submitted

ContactMarc Hainke

Foto of the furnace ARTEMIS and the corresponding numerical model in CrysVUN

Global Simulation of the TRI-SI Processfor the Production of Photovoltaic Silicon

11.07.03

The photovoltaic marketconsists currently to 90% ofsolar cells made from single andpolycrystalline Silicon. Siliconfulfills a lot of requirements likeefficiency, long term stability,availability of large areas,availability at all, environmentalcompatibility except the still toohigh production costs. In thelaboratories single crystalline Sisolar cells (4cm2) have beenmanufactured having anefficiency of 24%. Thetheoretical maximum efficiencyis 28% to 29%. In industrialproduction an efficiency of14% to 16% is reached usingsingle crystalline Si solar cells(100 cm2).

However, the production ofsingle crystalline Si is relativeexpansive and thus moneyconsuming. Today over 55% ofthe production costs of a solarcell module are caused by theproduction of the Si wafer, onthe other hand only 12% arecaused by the processing of thecells and 35% by the modulefabrication. Thus, it is obvious,that the field of the waferproduction offers the largestpotential for the reduction ofthe costs. Especially a fastercrystal growth velocity as wellas a more low-loss sawing ofthinner wafers from the bulkcrystals are good startingpoints.

Bright prospects exist forachieving these two goals byusing the so – called tri –crystalline Si (Tri-Si) process,which is the most successful

alternative to thin film Si solarcells and which is studied bySiemens Solar since a fewyears.

In the Tri-Si Czochralski processcylinder shaped tri – crystallineSi rods are grown, whichconsist of three singlecrystalline rods with almostequal size and having pieshaped cross sections. Each ofthese segments is oriented inthe (110) direction which isparallel to the growth direction.Two of the three grainboundaries are ordinary twinboundaries, whereas the thirdboundary is a twin boundary of2nd order. Tri-Si wafers cutperpendicular from the rodhave three visible grain

boundaries, which are arrangedwith angles of almost 120° inform of a Mercedes star. Itresults from this specialgeometry, that the (111) slipplanes of all grains cancel eachother which counteracts ashivering along these planes.

Therefore, the Tri-Si structurehas advantages during crystalgrowth (stability of thestructure for multiple chargingand high growth velocities) aswell as during sawing andwafering. Thus Tri-Si rods canbe sawed much thinner at thesame yield as single crystallinewafers.

The successful industrial use ofthe Tri-Si process depends

Tri-Si crystal grown by Siemens Solar for solar cells

Global Simulation of the TRI-SI Processfor the Production of Photovoltaic Silicon

11.07.03

strongly, whether it is possibleto reduce the usually highercosts of the Czochralski processby more efficient productivityand yield. Therefore, thegrowth conditions propertieshave to be optimized to achievea faster growth of the Tri-Sicrystals and at the same time toresult in equal or bettermechanical and electricalproperties.

Within this project numericalsimulations of the furnaceavailable at Siemens Solar havebeen performed andsuggestions have been madefor an aimed change of thegeometry. Further simulationsof the thermal conditions aswell as their influence on thedefect formation in the crystals

should contribute to a furtheroptimization of the process.These simulations will beconducted by modelexperiments at Siemens Solar inorder to validate the numericalmodel. The final goal is toelaborate process windowswhich allow a higher materialquality and higher productivityduring the production of Tri-Sicrystals. Thereby, the focus ison the solution of the questionwhich process parametersresult in higher pulling ratesunder retention orimprovement of the mechanicaland electrical properties. The 3year project is financed by theBMBF and Siemens Solar.

ContactMichael Krause

Bending of s/l interface numerically calculated versus crystal lengths for two different geometries of the puller

R&D Projects in 2000

11.07.03

Bulk Growth of GaAs, InP, Si, CaF2,and solar cell materialsexperimentalResearch project: Growth of lowdislocation GaAs crystals with 3" and4" diameter by the Vertical Bridgman/Gradient-Freeze methodFunded by: BMBF (FreibergerCompound Materials)

Research project: Development of acrystal growth process for InP(2" bythe Vertical Gradient-Freeze methodFunded by: Wafer Technology Ltd.

FhG-Research project: Crystal growthand processing of Si – wafer with300mm diameterFunded by: BMBF (Wacker Siltronic)

FhG-Research project:Development and process optimisationof CaF2 for the 157nm applicationFunded by: BMBF (SchottMikrolithographie)

FhG-Research project:Development and construction of R&Dequipment for the growth CaF2 for the157nm applicationFunded by: BMBF (SchottMikrolithographie)

Research project: Production ofCuIn(S,Se)2-Chalkopyrite-Crystals bySolution Growth and Liquid PhaseEpitaxy as well as opto-electronicCharacterisation of DefectsFunded by: DFG

Research project: Processing of CIS:optimisation and characterisationFunded by: Siemens Solar, BayerischeForschungsstiftung

Numerical simulationResearch project: Use of magneticfields for the simulation of microgravityconditions at diffusive heat and masstransportFunded by: DLR

Research project: High performancecomputer codes and their applicationto optimize crystal growth processesFunded by: DFG

Research project: Efficient user friendlycomputation methods for the use forthe construction of industry furnacesFunded by: Bayer. Forschungsstiftung

Research project: Numerical modellingof metallurgical solidification processesby the coupling of the transportequations for porous media withmicrosegregation at dendrite growthFunded by: BayerischeForschungsstiftung

Research project: Numerical andprocess control for the industrialproduction of single crystalsFunded by: BMBF

FhG-Research project: Numericalsimulation for the support of processand furnace development for thegrowth of low dislocation GaAssubstrate crystals with 4" and 6"diameter by the VerticalBridgman/Gradient-Freeze methodFunded by: Freiberger CompoundMaterials (BMVG)

FhG-Research project: Furtherdevelopment of growth processes forlarge GaAs substrate crystals bynumerical simulationFunded by: Freiberger CompoundMaterials (BMVG)

FhG-Research project: Development ofa Point defect Simulation programmeand licence of the computer codeCrysVUNFunded by: MEMC

FhG-Research project: Developmentand licence of the computer codeSTHAMASFunded by: Super Silicon

FhG-Research project: Developmentand licence of the computer codeCrysVUNFunded by: Sumitomo Electrics

FhG-Research project: Developmentand licence of the computer codeCrysVUNFunded by: CAESAR (BMBF)

FhG-Research project: Developmentand licence of the computer codeCrysVUNFunded by: Institute of Crystal GrowthBerlin (BMBF)

FhG-Research project: Developmentand licence of the computer codeCrysVUNFunded by: Research CenterRossendorf

FhG-Research project: Developmentand licence of the computer codeCrysVUNFunded by: University Stuttgart

FhG-Research project: Global thermalsimulation of the Tri-Si Czochralskiprocess for the production of Si crystalsfor solar cellsFunded by: Siemens Solar (BMBF)

FhG-Research project: Study of grainstructure during solidification oftechnical alloys under diffusive andmagnetically controlled convectiveconditions with the help ofmicrogravity experimentsFunded by: DLR

FhG-Research project: Microstructureformation in technical alloys underdiffusive and magnetically controlledconvective conditionsFunded by: ESA

Equipment

11.07.03

Laboratory space:120 m2 laboratory space plusoffice and laboratories whichbelongs to the Department ofCrystal Growth of the"Fraunhofer Institute forIntegrated Circuits".

Main Equipment:

Crystal growth- 2 high-pressure Czochralski

pullers (up to 3" crystaldiameter, used for LECgrowth of InP and Czgrowth of Si)

- 3 high-pressure multi-zonecold wall furnaces (for 2" -6" crystal diameter, usedfor VGF growth of InP andVGF growth of GaAs)

- 1 multi zone furnace (usedfor growth of CaF2 crystals)

- 4 furnaces for solutiongrowth (for 1" crystaldiameter, used for growthof CuInSe2 by THM andSBM)

- Leybold sputter facility- 1 mirror furnace (for 1"

crystal diameter, used for FZgrowth of GaAs)

- 1 multi-zone furnace,designed for crystal growthunder the influence ofmagnetic fields (for 1"crystal diameter, used forthe VGF growth of Ge)

- 1 multi-zone furnace,designed for crystal growthon a centrifuge (for 1"crystal diameter, used forthe VGF growth of Ge)

- several tube furnaces forsample preparation

- 1 liquid phase epitaxyfacilityy

- centrifuge for experimentsunder high gravity(centrifuge radius 50-120cm, rotation speed 0-250rpm)

Analysis andcharacterization of materials• Optical/infrared microscope,

Reichert-Jung• Other different optical

microscopes• Mapping system for optical

spectroscopy ofsemiconductor wafers

• Interferometic profilometerfor surface analysis ofsemiconductor wafers

• X-ray Laue camera• Hall-measurement-system

(temperature dependent15K-650K)

• laterally resolved resistivitymeasurements by 4-point-probe-method andspreading resistance(resolution 20µm)

• Measurement system forcharacterisation of deepand shallow levels bycapacitance techniques (CV,DLTS) and by conductancetechniques (TSC, PICTS)

• Photoluminescence system(14K and 300K), IR-absorption, both systemssuitable for mapping

• Atomic absorptionspectrometry for traceanalysis

• Differential ThermalAnalysis for determinationof phase diagrams

• Differential ScanningCalorimetry forthermodynamic and kineticstudies

• 1 frequency converter(P=90kW, f=1...1000Hz)

Preparation andmetallography• Facilities for preparative

work related to III-Vcompound waferpreparation (grinder,annular saws, lapping andpolishing equipment)

• 2 evaporation systems• Sputtering systems

Others• 1 magnet for axial steady

field (inner diameter 50cm,Bmax = 0.2T)

• 2 magnets for rotatingfields (inner diameter 15cm,Bmax = 10mT)

• 1 magnet system forrotating fields (variablediameter)

• 1 Gaussmeter for magneticinduction measurements (3axes)

Publications since 1999

11.07.03

00BRB. Birkmann, M. Rasp, J. Stenzenberger, G. MüllerGrowth of 3" and 4" gallium arsenide crystals by the vertical gradientfreeze (VGF) methodJ. Cryst. Growth 211 (2000) 157-162

00VFD.Vizman, B. Fischer, J. Friedrich, G. Müller3D numerical simulation of melt flow in the presence of a rotating magnetic fieldInt. J. Num. Meth. Heat Fluid Flow 10, (2000) 366

00BKR. Backofen, M. Kurz, G. MüllerProcess Modelling of the Industrial VGF Crystal Growth Process Using the Software Package CrysVUN++J. Cryst. Growth 211, (2000) 202-206

00KMM. Kurz, G. MüllerControl of Thermal Conditions during Crystal Growth by Inverse ModellingJ. Cryst. Growth, 208, (2000) 341-349

00MBM. Metzger, R. Backofen,Optimal temperature profiles for annealing of GaAs-CrystalsJournal of Crystal Growth220, (2000) 6-15

00FKCh. Frank, K. Jacob, M. Neubert, P. Rudolph, J. Fainberg, G. MüllerTemperature field simulation and correlation to the structural quality of semi-insulating GaAs crystals grown by the vapour pressurecontrolled Czochralski method (VCz)J. Cryst. Growth 213, (2000) 10-18

00VMA. Voigt, M. MetzgerNumerical Simulation and Control of Industrial Crystal Growth by the Czochralski and Vertical Gradient Freeze Methodcaesar preprint 2000-2, (2000)

00FFB. Fischer, J. Friedrich, U. Hilburger, G. MüllerSystematic study of buoyant flows in vertical melt cylinders under the influence of rotating magnetic fieldsProc. EPM2000, Nagoya, Japan, (2000) 497-502

00FF2J. Friedrich, B. Fischer, O. Gräbner, D. Vizman, G. MüllerHigh performance computing for the analysis of the influence of steady magnetic fields on convective heat transfer in Czochralski melts:comparison to experimental resultsProc. 4th Int. PAMIR Conference, Presqu`ile de Giens, France (2000) 239-244

00VFD. Vizman, J. Friedrich, G. MüllerThree dimensional numerical simulation of thermal convection in a Czochralski meltB. Sunden and C.A. Brebbia (Editors), Advanced Computational Methods in Heat Transfer VI, (2000) 137-146

99MRMühe A., Backofen R., Fainberg J., Müller G., Dornberger E., Tomzig E., v. Ammon W.Oxygen Distribution in Silicon Melt During a Standard Czochralski Process Studied by Sensor Measurements and Comparison to NumericalSimulationJ. Crystal Growth 198/199 (1999)

99MMMüller G., Mühe A., Backofen R., Tomzig E., v. Ammon W.Study of Oxygen transport in Cz growth of siliconMicroelectronics Engineering 1, (1999) 135-147

Publications since 1999

11.07.03

99MEMetzger M.Existence for a Time-dependent Heat Equation with Non-local Radiation TermsMath.Meth.Appl.Sci. 22, (1999) 1101-1119

99LSLeicht M., Stenkamp D., Strunk H.P., Wolf D., Eisener B., Müller G.Nanoscopic crystallography of chalcopyrite CuInS2 by techniques of convergent-beam electron diffractionPhil Mag. A79, (1999) 1033-1043

99KPKurz M., Pusztai A., Müller G.Development of a new powerfull computer code CrysVUN++ especially designed for fast simulation of bulk crystal growth processesJ. Crystal Growth 198/199 (1999)

99FWFischer B., Wellein G., Müller G.3D time-dependent numerical simulation of buoyant convection in vertical melt cylinders under the influence of rotating magnetic fieldsIn: Annual Report LRZ Munic (1999)

99FMFriedrich J., Müller G.The influence of steady and alternating magnetic fields in crystal growth and alloy solidification: Industrial importance, current industrialR&D topics, links to microgravity researchESA SP 433 (1999) 309-314

99FLFriedrich J., Lee Y., Fischer B., Kupfer C., Vizman D., Müller G.Experimental and numerical study of Rayleigh-Benard convection affected by a rotating magnetic fieldPhysics of Fluids 11 (1999) 853-861

99FFFischer B., Friedrich J., Weimann H., Müller G.The use of time-dependent magnetic fields for control of convective flows in melt growth configurationsJ. Crystal Growth 198/199 (1999) 170-175

99FFFischer B., Friedrich J., Kupfer C., Müller G., Vizman D.Experimental and numerical analysis of the influence of a rotating magnetic field on convection in Rayleigh Benard configurationsIn: Transfer Phenomena in Magnetohydrodynamics and Electroconducting Flows, Kluwer, Dordrecht (1999) 279-294

99EWEisener B., Wagner M., Wolf D., Müller G.Study of the intrinsic defects in solution grown CuInSe2 crystals depending on the path of crystallizationJ. Crystal Growth 198/199, (1999) 321-324

99AHAmon J., Härtwig J., Ludwig W., Müller G.Analysis of Types of Residual Dislocations in the VGF Growth of GaAs with extremely low Dislocation Density (EPD << 1000cm-2)J. Crystal Growth, (1999) 367-373.

99ABAmon J., Berwian P., Müller G.Computer-Assisted Growth of Low-EPD GaAs with 3'' Diameter by the Vertical Gradient-Freeze TechniqueJ. Crystal Growth 198/199, (1999) 361-366.

Address:Prof. Dr. Georg MüllerCrystal Growth LaboratoryFAU-WW6, Martensstr. 7D-91058 Erlangen

or

Prof. Dr. Georg MüllerCrystal Growth LaboratoryFhG IIS-B, Schottkystr. 10D-91058 Erlangen

Phone: +49-9131-852-7636Fax: +49-9131-852-8495Email: georg.mü[email protected]: http://www6.ww.uni-erlangen.de/CGL

Access:By carUse A 3, exit Tennenlohe/Erlangen, follow signsfor Erlangen,after 2 km takeexit "Universität Südgelände".

By planeFrom Nürnberg (Nuremberg) airport use taxi (15 minutes) or bus lane 32to Nürnberg-Thon and lane 30 or 30Eto Erlangen Süd,(30 minutes).

By trainConvenient train services from NürnbergCentral Station to Erlangen.From Erlangen station use taxi (15 minutes)or bus lane 287 to Stettiner Strasse (30 minutes).

FHG-IIS-B Site

Universität Erlangen-Nürnberg

ContactProf. Dr. G. Müller, Crystal Growth Laboratory, Martensstr. 7, D-91058 ErlangenTel. + 49-9131-852-7636, Fax. +49-9131-852-8495, Email: [email protected]://www6.ww.uni-erlangen.de/CGL/

Universität Erlangen-Nürnberg