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1、IC工艺技术系列讲座第二讲PHOTOLITHOGRAPHY光刻1IC工艺技术2光刻讲座提要1. General 2. Facility (动力环境)3. Mask (掩膜版)4. Process step highlight (光刻工艺概述)5. BCD 正胶工艺6. History and 未来的光刻工艺2IC工艺技术2光刻1.GeneralMASKING Process (光刻工艺)n nPhotolithography Photolithography ( (光学光刻光学光刻) ) -Transfer a -Transfer a temporary pattern (resist)tem
2、porary pattern (resist)Defect controlDefect controlCritical dimension controlCritical dimension controlAlignment accuracyAlignment accuracyCross section profileCross section profile n nEtch Etch ( (腐蚀腐蚀) ) -Transfer a permanent pattern (Oxide, -Transfer a permanent pattern (Oxide, Nitride, MetalNitr
3、ide, Metal) )3IC工艺技术2光刻2.0 Facility requirementn nTemperature (Temperature (温度温度) ) 70 70 o oF Fn nHumidity (Humidity (湿度湿度) )45%45%n nPositive pressure (Positive pressure (正压正压) ) 0.02in/H0.02in/H2 2OOn nParticle control (Particle control (微粒微粒) ) Class 100Class 100n nVibration (Vibration (震动震动) )n
4、 nYellow light environment (Yellow light environment (黄光区黄光区) )n nDI water (DI water (去离子水去离子水) 17mhom) 17mhomn nCompress air and Nitrogen (Compress air and Nitrogen (加压空气加压空气, ,氮气氮气) )n nIn house vacuum(In house vacuum(真空管道真空管道) )4IC工艺技术2光刻3.0 Mask (掩膜版) n nDesign n nPG tapen nMask making Plate - q
5、uartz, LE glass, Soda line glassPlate - quartz, LE glass, Soda line glass Coating - Chrome, Ion oxide, EmulsionCoating - Chrome, Ion oxide, Emulsion Equipment - E-beam, Pattern generatorEquipment - E-beam, Pattern generatorn nMask storage - -Anti static BoxAnti static Box5IC工艺技术2光刻Pellicle6IC工艺技术2光刻
6、Pellicle protection7IC工艺技术2光刻4.0 光刻工艺概述1. 1.Prebake and HMDS ( (前烘前烘) )2. 2.Resist coating ( (涂胶涂胶) )EBR (EBR (去胶边去胶边), soft bake,), soft bake,3. Exposure ( (曝光曝光) )Alignment (Alignment (校正校正) )4. Develop ( (显影显影) )Post e-bake, Hard bake, backside rinse Post e-bake, Hard bake, backside rinse 5. Deve
7、lop inspection ( (显检显检) )8IC工艺技术2光刻4.1 Prebake and HMDS treatmentPurpose of Pre-bake and HMDS treatment is to improve the resist Purpose of Pre-bake and HMDS treatment is to improve the resist adhesion on oxide wafer. HMDS is adhesion promoter especially adhesion on oxide wafer. HMDS is adhesion pro
8、moter especially designed for positive resist.designed for positive resist.HMDS (Hexamethyldisilane) can be applied on the wafers byHMDS (Hexamethyldisilane) can be applied on the wafers by1. 1. Vapor in a bucketVapor in a bucket2. 2.vapor in a vacuum boxvapor in a vacuum box3. 3.Directly dispense o
9、n waferDirectly dispense on wafer4. 4.YES system - in a hot vacuum systemYES system - in a hot vacuum system5. 5.Vapor in a hot plate (with exhaust)Vapor in a hot plate (with exhaust)Too much HMDS will cause poor spin, vice versa will cause resist liftingToo much HMDS will cause poor spin, vice vers
10、a will cause resist lifting9IC工艺技术2光刻4.2 Resist Coating (涂胶)Resist coating specification (Resist coating specification (指标）指标）n nThicknessThickness（厚度）（厚度）0.7u 0.7u 2.0u (3.0 2.0u (3.0以上以上for Pad layer)for Pad layer)n nUniformityUniformity（均匀度）（均匀度）+ + 50A 50A + +200A200An nSize of EBR Size of EBR （
11、去胶边尺寸）（去胶边尺寸）n nParticleParticle（颗粒）（颗粒）20 per wafer20 per wafern nBackside contamination(Backside contamination(背后污染）背后污染）三个主要因数影响涂胶的结果三个主要因数影响涂胶的结果1. 1.ResistResistProduct (Product (产品）产品） Viscosity Viscosity （粘度）（粘度）2. 2.SpinnerSpinnerDispense method Dispense method （涂胶方法）（涂胶方法）Spinner speed (RPM
12、) Spinner speed (RPM) （转速）（转速）Exhaust Exhaust （排气）（排气）Soft bake temperature Soft bake temperature （烘温）（烘温）3. 3.FacilityFacilityTemperature Temperature （室温）（室温）Humility Humility （湿度）（湿度）10IC工艺技术2光刻4.2.1Coater (涂胶机）Equipment module and special featuren nPre-bake and HMDS - Hot/Cold platePre-bake and H
13、MDS - Hot/Cold platen nResist dispense - Resist pumpResist dispense - Resist pumpn nRPM accuracy - MotorRPM accuracy - Motorn nEBR - Top/bottomEBR - Top/bottomn nHot plate - soft bake temperature accuracyHot plate - soft bake temperature accuracyn nExhaustExhaustn nWaste collectionWaste collectionn
14、nTemperature/Humidity control hoodTemperature/Humidity control hoodn nTransfer system - Particle and reliabilityTransfer system - Particle and reliabilityn nProcess step and process program - FlexibleProcess step and process program - Flexible11IC工艺技术2光刻SVG 8800升降机升降机涂胶涂胶HMDSHMDS热板热板冷板冷板升降机升降机升降机升降机
15、升降机升降机涂胶涂胶热板热板热板热板升降机升降机升降机升降机升降机升降机升降机升降机涂胶涂胶热板热板冷板冷板HMDSHMDS冷板冷板冷板冷板冷板冷板涂胶涂胶热板热板热板热板升降机升降机升降机升降机显影显影热板热板热板热板热板热板冷板冷板4.2.2 Coater (涂胶机）combination12IC工艺技术2光刻4.2.3 Coater (涂胶机）Resist dispense methodsn nStatic Static n nDynamicDynamicn nRadialRadialn nReverse radialReverse radialResist pump (Volume c
16、ontrol - 2cc/wafer and dripping)(Volume control - 2cc/wafer and dripping)n nBarrel pump -TritekBarrel pump -Tritekn nDiaphragm pump - MilliporeDiaphragm pump - Milliporen nN2 pressure control pump - IDLN2 pressure control pump - IDLn nStep motor control pump - Cybot Step motor control pump - Cybot n
17、 nsize of dispense head size of dispense head 13IC工艺技术2光刻4.2.4 Coater (涂胶机）rpm (转速） and acceleration （加速） n nMaximum speed - Up to 10000 rpmMaximum speed - Up to 10000 rpmn nStability - day to dayStability - day to dayn nAcceleration - controllable number of stepsAcceleration - controllable number o
18、f stepsn nReliability - time to replacementReliability - time to replacementEBR (Edge bead removal)（清边）n nMethod - Top EBR or Bottom EBR or Top and Method - Top EBR or Bottom EBR or Top and bottom EBRbottom EBRn nProblem - DrippingProblem - Drippingn nChemical - Acetone, EGMEA, PGMEA, Chemical - Ace
19、tone, EGMEA, PGMEA, ETHLY-LACTATEETHLY-LACTATE14IC工艺技术2光刻 Resist Typen nNegative resistNegative resistn nPositive resistPositive resistG-lineG-linei i linelinereverse imagereverse imageTAC - top anti-reflective coatingTAC - top anti-reflective coatingBARLI - bottom anti-reflective coatingBARLI - bot
20、tom anti-reflective coatingn nChemical amplification resistChemical amplification resistn nX ray resistX ray resist15IC工艺技术2光刻 4.3 .1 Exposure (曝光) Transfer a pattern from the mask (reticle) to resistTransfer a pattern from the mask (reticle) to resistGoalGoal1. 1.Critical Dimension control (CD)Crit
21、ical Dimension control (CD)条宽条宽2. 2.Alignment Alignment 校准校准- Mis-alignment, run in/out- Mis-alignment, run in/out3. 3.Pattern distortion Pattern distortion 图样变形图样变形- Astigmatism- Astigmatism4. 4.Cross section profile Cross section profile 侧面形貌侧面形貌- side wall angle- side wall angle5. 5.Defect freeDe
22、fect free无缺陷无缺陷Equipment/mask/resist selectionEquipment/mask/resist selection1. 1.Resolution Resolution 分辨率分辨率- Expose character, Light source (wavelength), - Expose character, Light source (wavelength), N/A,N/A,2. 2.Auto-alignment skill Auto-alignment skill 自动校准技术自动校准技术- Light field, dark field, la
23、ser- Light field, dark field, laser3. 3.MaskMask掩膜版掩膜版- e-beam master, sub-master, spot size, quartz - e-beam master, sub-master, spot size, quartz plate, defect density, CD requirementplate, defect density, CD requirement4. 4.Resist selection Resist selection 胶选择胶选择16IC工艺技术2光刻4.3.2Exposure (曝光) Ali
24、gner Technology1. 1.Contact print (Contact print (接触）接触）Soft contact, hard contact, proximitySoft contact, hard contact, proximity2. 2.Scanner (Scanner (扫描）扫描）3. 3.Stepper (Stepper (重复）重复）1X, 2X , 4X, 5X, 10X1X, 2X , 4X, 5X, 10X4. 4.Step Step Scan ( Scan (重复扫描重复扫描) )4X - reticle move, wafer move, 4X
25、 - reticle move, wafer move, reticle/wafer movereticle/wafer move5. 5.X ray (XX ray (X光）光） 1:16. 6.E-beam (E-beam (电子束）电子束）- Direct write - Direct write 17IC工艺技术2光刻4.3.3Exposure (曝光) Contact print (接触）1. 1.Most of use for negative resist process - for Most of use for negative resist process - for 5u
26、 process and can be push to 3u.5u process and can be push to 3u.2. 2.Positive resist can print smaller than 3u, and Positive resist can print smaller than 3u, and deepUV can push to 1u, but very high defectdeepUV can push to 1u, but very high defect3. 3.Equipment:Equipment:- Canon PLA 501- Canon PLA
27、 501- Cobilt- Cobilt- Kasper- Kasper- K&S- K&S18IC工艺技术2光刻Contact print -Canon 50119IC工艺技术2光刻4.3.4Exposure (曝光) Scanner (扫描）1. Most of use for G line Positive resist process - for 3u process and can be push to 2u.2. Negative resist can print smaller than 4u 3. Equipment:- Canon MPA 500, 600- Perkin E
28、lmer 100, 200, 300, 600, 700, 900 20IC工艺技术2光刻PE 240 Scanner21IC工艺技术2光刻Canon 600 Scanner22IC工艺技术2光刻4.3.5Exposure (曝光) Stepper (重复） 1. 1.G line positive resist - for 0.8u process G line positive resist - for 0.8u process 2. 2.i line positive resist - 0.5u processi line positive resist - 0.5u process3.
29、 3.i line resist plus phase-shift mask - can be i line resist plus phase-shift mask - can be pushed to 0.35pushed to 0.354. 4.deepUV resist process deepUV resist process - 0.35u and below- 0.35u and below5. 5.Equipment:Equipment:- Ultratech- Ultratech- Canon - Canon - Nikon- Nikon- ASML- ASML23IC工艺技
30、术2光刻4.3.6Exposure (曝光) 6ASML Stepper list ModelModelWavelength ResolutionWavelength ResolutionASML 2500 ASML 2500 g g0.80.8ASML 5000ASML 5000ASML 5500 ASML 5500 20,22,25,60,60B,80,80B 20,22,25,60,60B,80,80Bi i0.550.55ASML 5500 ASML 5500 100,100C,100D,150 100,100C,100D,150i i0.450.45ASML 5000 ASML 50
31、00 200,200B,250,250B 200,200B,250,250B UV UV0.350.35ASML 5500 ASML 5500 300,300B,C,D,TFH 300,300B,C,D,TFH UV UV0.250.25ASML 5500-900 Step-ScanASML 5500-900 Step-ScanUVUV24IC工艺技术2光刻4.4.1Develop (显影）Develop processDevelop process1. 1.Post expose bakePost expose bake2. 2.Resist DevelopResist Develop3.
32、3.DI water rinse DI water rinse 4. 4.Hard BakeHard BakeDevelop equipmentDevelop equipment1. 1.Batch developBatch develop2. 2.Track developTrack developDevelop chemicalDevelop chemical1. 1.KOH KOH 2. 2.Metal free (TMAH) - Metal free (TMAH) - TetramethylamoniahydroxideTetramethylamoniahydroxide3. 3.We
33、tting agent - with/withoutWetting agent - with/without4. 4.Concentration - 2.38%TMAHConcentration - 2.38%TMAHTrack develop methodTrack develop method1. 1.SpraySpray2. 2.SteamSteam3. 3.Signal-PaddleSignal-Paddle4. 4.Double-PaddleDouble-Paddle25IC工艺技术2光刻4.4.2 Develop (显影）Develop Track1. Temperature co
34、ntrol water jacket for Develop line2. Develop pump/develop pressure canister3. Exhaust4. Hot plate temperature control5. Pre-wet - process program26IC工艺技术2光刻4.4.3Develop (显影）CD control in developing1. 1.Post bake processPost bake process2. 2.Develop Time Develop Time 3. 3.Concentration of developer
35、chemical (Higher Concentration of developer chemical (Higher fast)fast)4. 4.Developer temperature (lower faster 1Developer temperature (lower faster 1o o C/0.1u)C/0.1u)5. 5.Develop recipe - pre-wet, paddle, rotationDevelop recipe - pre-wet, paddle, rotation6. 6.Age of the develop chemicalAge of the
36、develop chemical7. 7.Rinse - DI water pressureRinse - DI water pressure8. 8.Hard bake temperatureHard bake temperature27IC工艺技术2光刻4.5.1Develop Inspection Tool for inspection1. 1.MicroscopeMicroscopeManually loadingManually loadingAutomatic loadingAutomatic loading2. 2.UV lamp UV lamp Manually loading
37、Manually loadingAutomatic loadingAutomatic loading3. 3.CD measurement equipmentCD measurement equipmentManually measuring system - Vicker, Manually measuring system - Vicker, Automatic measuring system - NanolineAutomatic measuring system - NanolineCD SEMCD SEM28IC工艺技术2光刻4.5.2Develop Inspection Insp
38、ection items1. Layer name2. Alignment3. Run in/out4. Pattern distortion5. Pattern integrity6. Defects lifting, particle, discoloration, scumming, bridging, excess resist, scratch7. CD (critical dimension) 29IC工艺技术2光刻Nanoline - for CD measurement30IC工艺技术2光刻Hitachi 8860 - CD SEM31IC工艺技术2光刻Leitz Micros
39、cope inspect station32IC工艺技术2光刻Autoload UV inspection system 33IC工艺技术2光刻5.0 BCD 正胶工艺Equipment Equipment SSI, SVG8800, SVG 90SSI, SVG8800, SVG 90Process stepProcess steppre-bake/HMDS/cold platepre-bake/HMDS/cold platespin (5000rpm) -dynamic dispensespin (5000rpm) -dynamic dispense -top (bottom) side
40、EBR(2mm) -top (bottom) side EBR(2mm)soft bake (100soft bake (100o oC)/cold/palteC)/cold/palteResist/specResist/specShipley Shipley 6112 (1.2u) 6112 (1.2u) 1818 (1.8u 1st metal)1818 (1.8u 1st metal) 6818 (2.4u 2nd metal)6818 (2.4u 2nd metal)6118 (2.9u Pad)6118 (2.9u Pad)6124 (3.6u-4.5u ST)6124 (3.6u-
41、4.5u ST)Everlight Everlight 533(1.2) 533(1.2) Uniformity -Uniformity -+ 300A 300AResist coatingResist coating升降机升降机冷板冷板HMDSHMDS涂胶涂胶热板热板冷板冷板升降机升降机34IC工艺技术2光刻SVG 9035IC工艺技术2光刻SVG 880036IC工艺技术2光刻5.1.1Positive Resist (正胶）Component (成分）n nResin Resin （树脂）（树脂）Diazonaphthoquinone(DNQ)/novolakDiazonaphthoqu
42、inone(DNQ)/novolakn nPhoto-sensitizer Photo-sensitizer （感光剂）（感光剂）n nSolvent Solvent （溶剂）（溶剂）n nDye Dye （染料（染料）Manufacturing (制造商）n nKodak Kodak Hunt Hunt Ash chemical (USA) Ash chemical (USA)n nTOK (Japan)TOK (Japan)n nJSR (Japan)JSR (Japan)n nShipley (USA)Shipley (USA)n nAZ (USA, Germany)AZ (USA, G
43、ermany)n nSumitomo (Japan)Sumitomo (Japan)n nEverlight (Taiwan)Everlight (Taiwan)37IC工艺技术2光刻5.1.2Positive Resist (正胶）Product Name and feature (产品称与特性）以以everlight (everlight (永光）正胶为例永光）正胶为例Product SeriesProduct SeriesEPG 510 SeriesEPG 510 SeriesExpose wavelengthExpose wavelengthG-Line (435nm)G-Line (
44、435nm) ThicknessThicknessNameName 2000rpm 5000rpm 2000rpm 5000rpmViscosity Viscosity （粘度）（粘度）EPG 510 - 12 cpEPG 510 - 12 cp1.25u1.25u0.80u0.80uEPG 512 - 21.5 cpEPG 512 - 21.5 cp2.00u2.00u1.25u1.25uEPG 516 - 50 cpEPG 516 - 50 cp3.25u3.25u2.00u2.00uEPG 518 - 105 cpEPG 518 - 105 cp4.50u4.50u2.75u2.75uE
45、PG 519 - 460 cpEPG 519 - 460 cp9.00u9.00u5.5u5.5u Resolution (Resolution (分辨率）分辨率） 0.8u (0.55u - the smallest)0.8u (0.55u - the smallest)Depth of Focus (Depth of Focus (聚焦深度）聚焦深度）+ + 1.4u (1.0u line/space) 1.4u (1.0u line/space)Sensitivity (Sensitivity (感光度）感光度） Eth = 60 mj/cm2Eth = 60 mj/cm2Eop = 9
46、0 mj/cm2Eop = 90 mj/cm238IC工艺技术2光刻5.1.4Positive Resist (正胶）Select a positive resist1. 1.Resolution Resolution （分辨率）（分辨率）2. 2.Resist thickness - Spin curve Resist thickness - Spin curve （厚度）（厚度）3. 3.Photo speedPhoto speed( (曝光速度曝光速度) )4. 4.Expose latitude Expose latitude ( (曝光宽容度曝光宽容度) )5. 5.Adhesion
47、 Adhesion （粘附性）（粘附性）6. 6.Reflective notch Reflective notch （反射缺口）（反射缺口）6. 6.Metallic content Metallic content （金属含量）（金属含量）7. 7.Thermal stability Thermal stability （热稳定性）（热稳定性）8. 8.Plasma resistance Plasma resistance （抗腐蚀能力）（抗腐蚀能力）9. 9.How easy to be removed How easy to be removed （清除能力）（清除能力）10.10.
48、Price Price （價格）（價格）39IC工艺技术2光刻5.2 ExposeEquipment Ultratech stepper 1100 (6”)Ultratech stepper 1500 (6”)Canon 600 (6”)Perkin Elmer 240 (4”)40IC工艺技术2光刻Positive Resist reaction during expose41IC工艺技术2光刻Positive Resist reaction during expose42IC工艺技术2光刻5.2.1Ultratech Stepper Ultratech steppern nG-line G
49、-line n nN/A - 0.24 and 0.31N/A - 0.24 and 0.31n n1:1 print ratio1:1 print ration n3 X 5 inch reticle - 3, 4, 5, 7 field3 X 5 inch reticle - 3, 4, 5, 7 fieldn n4u depth of focus4u depth of focusn nBlind step can be push to 5u (no spec)Blind step can be push to 5u (no spec)n nCenter of array Center o
50、f array + + 50u 50u n nDark field alignmentDark field alignmentn nSite by Site alignment Site by Site alignment n nAlignment target Alignment target *oat - 4mm X 4mm*oat - 4mm X 4mm*K/T - 200u X 200u*K/T - 200u X 200u43IC工艺技术2光刻Ultratech Stepper 110044IC工艺技术2光刻Ultratech Stepper 1500/170045IC工艺技术2光刻5
51、.2.2Ultratch stepper specification46IC工艺技术2光刻UTS-Reticle and Job fileGuideGuideFiducialsFiducials47IC工艺技术2光刻UTS-primary lens48IC工艺技术2光刻UTS AlignmentOptic49IC工艺技术2光刻Ulratech stepper site by site alignment50IC工艺技术2光刻UT alignment proceduren nLoad job file into computerLoad job file into computern nLoad
52、 reticleLoad reticleStart Start n niducials alignment - Guide, rotation(1500)iducials alignment - Guide, rotation(1500)n nOAT alignment OAT alignment OAT size = 4mmX4mmOAT size = 4mmX4mmFast and slow scan 1000uFast and slow scan 1000un nSide by side alignment Side by side alignment Key and target si
53、ze 200uX200uKey and target size 200uX200ushot scan 20ushot scan 20ulong scan 100u (80u)long scan 100u (80u)n nAuto-focusAuto-focusGoble or localGoble or localn nFailure alignment Failure alignment SkipSkipExposeExposeZmodeZmode51IC工艺技术2光刻5.3 Perkin Elmer alignern nMicalign PE 100Micalign PE 100n nMi
54、calign PE 200, 220, 240Micalign PE 200, 220, 240n nMicalign PE 300, 340, 340HTMicalign PE 300, 340, 340HTn nMicalign PE 500Micalign PE 500n nMicalign PE 600Micalign PE 600n nMicalign PE 700Micalign PE 700n nMicalign PE 900Micalign PE 900n nMicscan 100Micscan 100n nMicscan 200Micscan 200n nMicscan 30
55、0Micscan 300n nMicscan 400Micscan 40052IC工艺技术2光刻PE 240 Specification53IC工艺技术2光刻PE 24054IC工艺技术2光刻PE 240PMPMn nCenter of curvatureCenter of curvaturen nParallelismParallelismn nLight intensityLight intensityn nFocusFocusn nDistortionDistortionn nMask/wafer centeringMask/wafer centeringn nView opticVie
56、w opticn nHPC rebuildHPC rebuildn nCooling air flow rateCooling air flow raten nVibration from HPCVibration from HPCFacilityFacilityn nVibration from Vibration from environmentenvironmentn nTemperature control Temperature control hoodhoodProcessProcessn nReference waferReference wafern nAperture sel
57、ectionAperture selectionn nResist build up on XYO Resist build up on XYO pinspinsn nRoof mirror cleaningRoof mirror cleaningn nMask heat up during Mask heat up during exposeexpose55IC工艺技术2光刻PE - Focus wedge mask56IC工艺技术2光刻PE - distortion57IC工艺技术2光刻PE - Projection optic58IC工艺技术2光刻PE Mercury lamp59IC工
58、艺技术2光刻PE - Adjustable slit60IC工艺技术2光刻PE alignment proceduren nSet scann nLoad maskn nLoad wafern nSwitch to maskn nUse microscope and carriage movement to find the alignment mark on mask (Test die)n nMove mask only to align the wafern nSwitch to wafern nMove wafer align to mask61IC工艺技术2光刻5.4.1Resist
59、 develop Equipment Equipment SSI, SVG8800, SVG 90SSI, SVG8800, SVG 90Process stepProcess step pose-e bake/cold platepose-e bake/cold platedevelop - double paddle develop - double paddle - DI water rinse- DI water rinse - back N- back N2 2/rinse/rinsehard bake (110-130hard bake (110-130o oC)/cold/pal
60、teC)/cold/palteDeveloperDeveloperTMAH 2.35%TMAH 2.35%升降机升降机冷板冷板热板热板冷板冷板升降机升降机热板热板显影显影62IC工艺技术2光刻SVG 880063IC工艺技术2光刻SVG 9064IC工艺技术2光刻5.4.2 Resist develop Equipment Equipment Develop sinkDevelop sinkEquipment set upEquipment set upTemperatureTemperatureN2 blanketN2 blanketFilter sizeFilter sizeFilter
61、changeFilter changeDeveloperDeveloperTMAH 2.38%TMAH 2.38%Develop change Develop change Process step Process step batch develop - immerse batch develop - immerse (1(1 & 15 & 15” ”) )QDR DI water rinse (8 QDR DI water rinse (8 cycles)cycles)hard bake (110-hard bake (110-130130o oC)/cold/palteC)/cold/p
62、alte65IC工艺技术2光刻6. History and 未来的光刻工艺Will imprint technology replace photolithography?Will imprint technology replace photolithography?n nIn 1798, image was transferred by stone plateIn 1798, image was transferred by stone platen n1940, Bell Lab used resist developed by Eastman Kodak1940, Bell Lab u
63、sed resist developed by Eastman Kodakn n1960, San Francisco bay area becomes the silicon valley - AT &T, Raytheon, 1960, San Francisco bay area becomes the silicon valley - AT &T, Raytheon, Fairchild, Negative resist Fairchild, Negative resist contact print process wildly was used. contact print pro
64、cess wildly was used. n nEnd of 1970-early of 1980, positive resist End of 1970-early of 1980, positive resist Projection print (Perkin Elmer Projection print (Perkin Elmer Micalign) started to be used in production. Bay area became cloudy - Micalign) started to be used in production. Bay area becam
65、e cloudy - National, Intel and AMD. Outside bay area had Motolora, TI, IBM.National, Intel and AMD. Outside bay area had Motolora, TI, IBM.n nFrom 1970 to early 2000, the technology of semiconductor is developed very From 1970 to early 2000, the technology of semiconductor is developed very fast. Th
66、e smallest feature size from 10u reduced to 0.09u. 0.25u and 0.35u fast. The smallest feature size from 10u reduced to 0.09u. 0.25u and 0.35u products were running mass production every where -USA, Europe, Japan, products were running mass production every where -USA, Europe, Japan, Taiwan, KoreaTai
67、wan, Korea i-line,and deepUV - 5X stepper and step-scan (4X) aligner i-line,and deepUV - 5X stepper and step-scan (4X) aligner became the major tools.became the major tools.n nNow, 0.09u technology become mature. 0.065u, 0.045u and 0.035u technology Now, 0.09u technology become mature. 0.065u, 0.045
68、u and 0.035u technology are being developed. Immersion lithography and imprint technology will be are being developed. Immersion lithography and imprint technology will be used to print these nano feature.used to print these nano feature.n nImprint technology claims that it is able to print 0.01u (1
69、0nm) - It may be the Imprint technology claims that it is able to print 0.01u (10nm) - It may be the future masking. future masking. 66IC工艺技术2光刻6.1 History n n Lithography, as used in the manufacture of the integrated circuit, is the process Lithography, as used in the manufacture of the integrated
70、circuit, is the process of transferring geometric shapes on a mask to the surface of a silicon wafer. These of transferring geometric shapes on a mask to the surface of a silicon wafer. These shapes make up the parts of the circuit, such as gate electrodes, contact windows, shapes make up the parts
71、of the circuit, such as gate electrodes, contact windows, metal interconnections, and so on. Although most lithography techniques used today metal interconnections, and so on. Although most lithography techniques used today were developed in the past 40 years, the process was actually invented in 17
72、98; in this were developed in the past 40 years, the process was actually invented in 1798; in this first process, the pattern, or image, was transferred from a stone plate (the word litho first process, the pattern, or image, was transferred from a stone plate (the word litho comes from).comes from
73、).n n The first practical two dimensional device patterning on a silicon wafer was The first practical two dimensional device patterning on a silicon wafer was actually carried out in the late 1940s at the Bell Lab. At that time, polyvinylcinnamate, actually carried out in the late 1940s at the Bell
74、 Lab. At that time, polyvinylcinnamate, developed by Eastman Kodak, was used as a resist. However, device yields were low developed by Eastman Kodak, was used as a resist. However, device yields were low because of the poor adhesion of the polyvinylcinnamate to the silicon and oxide because of the p
75、oor adhesion of the polyvinylcinnamate to the silicon and oxide surface. The Kodak chemists then turned to a synthetic rubber based material-a surface. The Kodak chemists then turned to a synthetic rubber based material-a partially cyclized isoprene and added a UV active sensitizer-a bis-aryl-azide
76、into it to partially cyclized isoprene and added a UV active sensitizer-a bis-aryl-azide into it to crosslink the rubber matrix and created a new class of photoresist material. Since the crosslink the rubber matrix and created a new class of photoresist material. Since the unexposed area of the new
77、material was the only part of the polymer matrix that will unexposed area of the new material was the only part of the polymer matrix that will dissolve in an organic solvent and yielding a negative image of the mask plate, dissolve in an organic solvent and yielding a negative image of the mask pla
78、te, therefore, the new material was then referred as the negative resist.therefore, the new material was then referred as the negative resist.n n The cyclized rubber/bisazide resist was widely used in the contact printing age. The cyclized rubber/bisazide resist was widely used in the contact printi
79、ng age. However, the contact mode of printing created severe wear of the mask plate and the However, the contact mode of printing created severe wear of the mask plate and the defect density of the photomask and the wafer was very high. The industry therefore defect density of the photomask and the
80、wafer was very high. The industry therefore decided to switch to contactless projection printing in 1972 for producing the 16k decided to switch to contactless projection printing in 1972 for producing the 16k DRAM.DRAM.n nProjection printing, however, was carried out in the Fraunhoffer or the so ca
81、lled far field Projection printing, however, was carried out in the Fraunhoffer or the so called far field diffraction region and the aerial image was much poorer than the contact or proximity diffraction region and the aerial image was much poorer than the contact or proximity method of printing. I
82、n order to preserve the same quality of image structure, the method of printing. In order to preserve the same quality of image structure, the contrast of the image material must be increased.contrast of the image material must be increased.n n 67IC工艺技术2光刻n n Lithographic lore has it that the diazon
83、aphthoquinone/novolak resist (the term Lithographic lore has it that the diazonaphthoquinone/novolak resist (the term novolak is derived from the Swedish word lak, meaning lacquer or resin and prefixed by novolak is derived from the Swedish word lak, meaning lacquer or resin and prefixed by the Lati
84、n word novo, meaning new) made their way from the blue print paper industry to the Latin word novo, meaning new) made their way from the blue print paper industry to the microelectronic through family ties: at that times, the offices of Azoplate, the the microelectronic through family ties: at that
85、times, the offices of Azoplate, the American outlet for Kalle printing plate, was located at Murray Hill, NJ, just across the American outlet for Kalle printing plate, was located at Murray Hill, NJ, just across the street from the famous Bell Labs. The father of a technician at Azoplate worked as a
86、 street from the famous Bell Labs. The father of a technician at Azoplate worked as a technician at Bell Labs. Apparently the father had complained one day about the poor technician at Bell Labs. Apparently the father had complained one day about the poor resolution quality of the solvent developed
87、resist system used at the Bell Labs and the son resolution quality of the solvent developed resist system used at the Bell Labs and the son had boasted the properties of the Azoplate DNQ/novolak material; anyway, one day the had boasted the properties of the Azoplate DNQ/novolak material; anyway, on
88、e day the father took a bottle of the material with him to the Bell Labs, and the age of the father took a bottle of the material with him to the Bell Labs, and the age of the DNQ/novolak resist began.DNQ/novolak resist began.n n The new material was marketed by Azoplate under the trade name of AZ T
89、he new material was marketed by Azoplate under the trade name of AZ photoresist. It was always referred as the positive resist for a positive tone of image would photoresist. It was always referred as the positive resist for a positive tone of image would be reproduced by the new material. The use o
90、f DNQ/novolak system increased rapidly be reproduced by the new material. The use of DNQ/novolak system increased rapidly after the introduction of the projection lithography. By 1980s, the DNQ resist had after the introduction of the projection lithography. By 1980s, the DNQ resist had completely s
91、upplanted the old negative resist as the workhorse of the semiconductor completely supplanted the old negative resist as the workhorse of the semiconductor industry in the high-end applications.industry in the high-end applications.n n The DNQ/novolak resist has held sway for 6 device generations, f
92、rom the The DNQ/novolak resist has held sway for 6 device generations, from the introduction of the 16K DRAM to the large scale production of the 64M DRAM in 1994 to introduction of the 16K DRAM to the large scale production of the 64M DRAM in 1994 to 1995. The success of such material was the indic
93、ative of it supreme performance and 1995. The success of such material was the indicative of it supreme performance and potential.potential.n n Today, it appears that it is not really the resolution which defines the limit of the Today, it appears that it is not really the resolution which defines t
94、he limit of the DNQ/novolak resist application, but rather the loss in the depth of focus with the ever DNQ/novolak resist application, but rather the loss in the depth of focus with the ever increasing NA of the stepper. Deep UV and chemical amplification negative tone resist increasing NA of the s
95、tepper. Deep UV and chemical amplification negative tone resist slowly erode the market place of the DNQ/novolak resist. By the end of the 1990s, the slowly erode the market place of the DNQ/novolak resist. By the end of the 1990s, the DNQ/novolak resist was no longer be used in the technologically
96、most advanced DNQ/novolak resist was no longer be used in the technologically most advanced applications-the printing of the critical levels of the 256M DRAM.applications-the printing of the critical levels of the 256M DRAM.68IC工艺技术2光刻6.2 Future Introduction of nanoimprint technologyIntroduction of
97、nanoimprint technologyn nFabricating microstructures and nanostructure is important in many fields of Fabricating microstructures and nanostructure is important in many fields of science and technology, including electronics, data storage, flexible displays, science and technology, including electro
98、nics, data storage, flexible displays, microelectromechanical systems, microfluidics, photonics and biosensors. microelectromechanical systems, microfluidics, photonics and biosensors. Traditionally, optical or electron beam lithography systems are used to print Traditionally, optical or electron be
99、am lithography systems are used to print the relevant structures. However, new printing methods such as imprint the relevant structures. However, new printing methods such as imprint lithography and soft lithography have recently been explored in some detail lithography and soft lithography have rec
100、ently been explored in some detail to lower the costs of fabricating low volumes of structures with very small to lower the costs of fabricating low volumes of structures with very small features and to increase the range of printing application.features and to increase the range of printing applica
101、tion.n nThe soft lithography schemes, in general, use a soft template pattern made of The soft lithography schemes, in general, use a soft template pattern made of silicone elastomer, polydimethylsiloxane (PDMS), which is placed into contact silicone elastomer, polydimethylsiloxane (PDMS), which is
102、placed into contact with the substrate in a variety of ways, to pattern a surface film, to transfer a with the substrate in a variety of ways, to pattern a surface film, to transfer a material, or for direct integration into the final part, with a range of innovative material, or for direct integrat
103、ion into the final part, with a range of innovative applications. Challenges in this area are generally concerned with the inherent applications. Challenges in this area are generally concerned with the inherent limitations of the PDMS material including resolution limitations when curing limitation
104、s of the PDMS material including resolution limitations when curing due to differences in thermal expansion between the master and mold; due to differences in thermal expansion between the master and mold; adhesion to common master materials like silicon; significant time, about an adhesion to commo
105、n master materials like silicon; significant time, about an hour, to fabricate a mold; elasticity of the mold, which may impact multilevel hour, to fabricate a mold; elasticity of the mold, which may impact multilevel alignment; insolubility with common solvents; contamination issues and alignment;
106、insolubility with common solvents; contamination issues and incompatibility with some organic materials.incompatibility with some organic materials.69IC工艺技术2光刻n nThe imprint methods utilize heat or UV curable liquids to mold patterns onto a The imprint methods utilize heat or UV curable liquids to m
107、old patterns onto a substrate from a rigid template. Research groups have demonstrated sub-substrate from a rigid template. Research groups have demonstrated sub-100nm resolution, some have down to 10nm. Imprint process; however, do not 100nm resolution, some have down to 10nm. Imprint process; howe
108、ver, do not transfer materials from the template to the substrate like the soft lithography transfer materials from the template to the substrate like the soft lithography schemes. Another hesitation with the imprint technique concerns the lifetime schemes. Another hesitation with the imprint techni
109、que concerns the lifetime of the master pattern. The problem is similar to that encountered in the of the master pattern. The problem is similar to that encountered in the contact photolithography, where it has been found that the defect free lifetime contact photolithography, where it has been foun
110、d that the defect free lifetime is only limited to less than 1000 passes, despite the application of coatings and is only limited to less than 1000 passes, despite the application of coatings and lubricants. This concern arises from the important requirements that the lubricants. This concern arises
111、 from the important requirements that the substrate must undergo significant contact and removal forces, that a rigid substrate must undergo significant contact and removal forces, that a rigid master pattern is used and that a tool is required to achieve good imprints.master pattern is used and tha
112、t a tool is required to achieve good imprints.n nIn Stanford University, a new class of high resolution pattern formation and In Stanford University, a new class of high resolution pattern formation and materials transfer printing strategy has been developed. This new method is materials transfer pr
113、inting strategy has been developed. This new method is collectively referred to as molecular transfer lithography. The new approach is collectively referred to as molecular transfer lithography. The new approach is based on the room temperature fabrication of water soluble polymer based on the room
114、temperature fabrication of water soluble polymer templates by spin casting a polyvinyl alcohol film forming solution to replicate templates by spin casting a polyvinyl alcohol film forming solution to replicate surface patterns. It is different than the imprint lithography and soft surface patterns.
115、 It is different than the imprint lithography and soft lithography by employing a water soluble template. The template dissolves at lithography by employing a water soluble template. The template dissolves at the conclusion of the image transfer, whereas in the alternative approaches, the conclusion
116、 of the image transfer, whereas in the alternative approaches, the template is reused. The use of the water soluble template for patterning the template is reused. The use of the water soluble template for patterning microstructure and nanostructure features enables a true contact printing microstru
117、cture and nanostructure features enables a true contact printing method wherein the master template does not actually contact the substrate method wherein the master template does not actually contact the substrate and the possibility of substrate to mask damage is eliminated and the integrity and the possibility of substrate to mask damage is eliminated and the integrity of the master pattern is preserved during the replication process.of the master pattern is preserved during the replication process.70IC工艺技术2光刻
