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1、Photo IntroductionAbstractLitho key wordLitho processLitho theoryLithography ability improvementOverlay introductionPhoto Trouble shooting introduction Machine Scanner: 扫描式曝光机扫描式曝光机SMIC 绝大多数的绝大多数的Scanner 是是ASML 生产的，他们的型号通常为：生产的，他们的型号通常为：750E，750F，400C，400D 等等等等 (据说，据说，750系列就代表此机台售价系列就代表此机台售价750万美金云云
2、万美金云云.)此外此外Scanner厂商还有厂商还有Cannon, Nikon等等Stepper: 步进式曝光机步进式曝光机ASML 现在几乎已经不再生产落后的现在几乎已经不再生产落后的Stepper，但但SMIC还是有一些还是有一些Stepper， 它们是它们是Canon生生产的产的I-line stepper。Stepper 在在OVL control 和和 Lens uniformity 方面不如方面不如Scanner,但速度的快捷和价格的低廉使其但速度的快捷和价格的低廉使其在一些非关键的层曝光上有成本的优势。在一些非关键的层曝光上有成本的优势。 ASML ScannerTrack: 涂
3、敷显影机涂敷显影机Track内除了涂敷和显影之外，还有相关的热板和冷板，以及内除了涂敷和显影之外，还有相关的热板和冷板，以及TARC或者或者BARC涂敷单元。涂敷单元。SMIC 使用的使用的Track为为 TEL所制。所制。 在现今的在现今的 Fab, 以上曝光机和显影机会联在一起成为一个以上曝光机和显影机会联在一起成为一个 “Photo In-line machine”相对而言的，相对而言的， BARC coater, PI coater 和和 PI developer 等等Track机台，因为不和机台，因为不和Scanner 或者或者Stepper相联，所以称为相联，所以称为“ Off-l
4、ine Track”OVL:量测层与层叠对的机台。量测层与层叠对的机台。Vendor 是是Accent 或者或者KLA等等CD SEM:Vendor是是Hitachi，KLA等等ADI: 显影后检查用的光学显微镜。显影后检查用的光学显微镜。 Vendor是是Nikon等等TrackMachine PRS window check0.1150.1250.1350.1450.1550.1650.1750.185260 270 280 290 300 310 320 330 340ENERGYCDCenterLBRBRTLTEnergy（能量）能量）影响线宽的最重要因素是曝影响线宽的最重要因素是曝光
5、能量，光能量， 通常对于通常对于Line 来说，来说，曝光能量越大，曝光能量越大， 线宽越小线宽越小（正光阻）。（正光阻）。调整能量也是制程工程师控调整能量也是制程工程师控制和调整线宽的最重要手段制和调整线宽的最重要手段Focus（焦距）焦距）焦距也是曝光过程中一个举足轻重的参数。焦距也是曝光过程中一个举足轻重的参数。它影响图形的横切面的形状，它影响图形的横切面的形状， 进而影响到进而影响到下一步制程的结果。下一步制程的结果。制程工程师一个很重要的工作就是找到某制程工程师一个很重要的工作就是找到某个层曝光的最佳个层曝光的最佳Focus， 并使制程条件保持并使制程条件保持在这附近。在这附近。Ke
6、y parameter of photo正光阻：曝光区域显影后光阻被去除正光阻：曝光区域显影后光阻被去除负光阻：曝光区域显影后光阻保留，非曝光区域光阻被去除（例：负光阻：曝光区域显影后光阻保留，非曝光区域光阻被去除（例：Polyimide）BARC: 底层防反射膜底层防反射膜 Bottom-anti-reflective coatingTARC: 顶层防反射膜顶层防反射膜 Top-anti-reflective coatingChemicalDevelop（显影）显影）曝光后的光阻呈酸性，曝光后的光阻呈酸性， 可以用碱性可以用碱性的显影液洗去，这就是显影过程。的显影液洗去，这就是显影过程。 显
7、影液由中央供应系统提供，一个显影液由中央供应系统提供，一个 Fab中所有的光刻制程采用相同的中所有的光刻制程采用相同的显影液。显影液。Nozzle: E2, H, E3, LD(more advance-)Puddle: wafer 在喷上显影液之后通常会静止浸泡一段时间，称为在喷上显影液之后通常会静止浸泡一段时间，称为 puddle.Rinse: 显影结束之后用显影结束之后用DI-water 喷淋，去除光阻残余。此步骤是决定喷淋，去除光阻残余。此步骤是决定photo defect level 的重要关键。的重要关键。 Develop（显影）显影）vLHP: Low Temperature H
8、ot PlatevHHP: High Temperature Hot Plate以上两者如右上图，只有温度范围不同以上两者如右上图，只有温度范围不同vCHP: Chilling Hot PlatevPCH: Precision Chilling Hot Plate vPHP: Precision Hot Plate以上三者如右下图，是专为以上三者如右下图，是专为PEB（温度温度&时时间精度要求很高）所用间精度要求很高）所用vHCH: Heating Cover Hot PlatevHEL: High Exhaust Hot Plate以上两者注重抽气效率，为以上两者注重抽气效率，为 PI 制程
9、专用制程专用Bake (烘烤烘烤)Soft bake（SB） The bake process after PR coatingPost expose bake (PEB) The bake after exposeHard bake(HB) The bake after developerHard wareReticle/Mask（光罩）光罩）光罩是光刻图形的来源。这些图光罩是光刻图形的来源。这些图形通常由客户给出数据，光罩厂形通常由客户给出数据，光罩厂制作。制作。右图是光罩的一个例子，除了中右图是光罩的一个例子，除了中央的数据区，边上还有许多辅助央的数据区，边上还有许多辅助用的用的Mark
10、.光罩平常放在一个光罩平常放在一个SMIF Pod 里里面，面，MA上下机台会打开检查或上下机台会打开检查或者用者用IRIS机台机台scan defect。即使小心使用，光罩仍会有尘埃、即使小心使用，光罩仍会有尘埃、缺损发生。定时地用缺损发生。定时地用Star light 和和IRIS 扫描光罩，是及时发现这些扫描光罩，是及时发现这些的有效方法的有效方法PSM: Phase shift maskMask grade: A,B,C,.G,H,I,J,K,L,Mask grade determine the CDU performance.MaskFrame cellFrame cell用于定义用
11、于定义 street内的内的CDBar，OVL Mark，test key等等FEM-0.33-0.26-0.19-0.12-0.050.020.090.160.23520.12340.11730.11460.11480.1258500.14760.14420.12690.12240.11980.12210.11820.14370.1514480.20.14380.13660.12940.12660.12420.13260.14430.1893460.20660.16110.13280.1340.12950.1270.13750.15510.1669440.17920.16280.14220.
12、14670.13480.13160.14990.15320.1639420.14720.15260.14130.14580.1572FEM: Focus Energy MatrixIn photo FEM, we not only check the CD data but also top view image to define the process windowFocusEnergyDOF and EL0.110.1150.120.1250.130.1350.140.1450.150.1550.160.1650.17-0.33-0.26-0.19-0.12-0.050.020.090.
13、160.23Focus525048464442AA windowDOF=0.12-(-0.20)=0.32DOF: depth of focusThe focus range of CD&profile can be accepted In the left chart, DOF=0.12-(-0.20)=0.32(um)0.10.1050.110.1150.120.1250.130.1350.140.1450.150.1550.16525048464442-0.33-0.26-0.19-0.12-0.050.020.090.160.23EL=(51-43.5)/48=15%EL=(51-43
14、.5)/48=15%EL: energy latitude The energy range of CD in spec. In the right chart, EL=(51-43.5)/48)x100%=15%UDOF and Common DOF0.12550.11470.11680.1110.11170.11290.11910.11890.11180.1140.11260.1120.1080.11450.10840.11490.12330.11670.16770.12160.13340.11480.1270.11260.11450.11330.11160.11420.11820.132
15、0.12220.13210.12670.11420.13570.12040.11950.11730.1180.11410.11860.10790.12460.12220.1210.12930.14750.13490.16990.12430.15010.12050.12850.11820.12360.11740.12610.11930.1230.13520.13790.13830.13150.15420.19990.13960.13280.12830.1180.11810.12510.1260.11750.11940.13690.13480.14280.15330.14150.17490.195
16、20.14250.13680.13110.13250.1220.12620.12640.12850.1220.13340.14780.13310.14760.14690.14830.1530.14750.17480.13280.13340.13520.13240.12480.12280.12830.12850.130.13720.15670.16680.15830.16510.16220.16010.14890.13450.13790.1350.13780.1290.1320.13430.15510.15610.14210.17860.1530.12870.13440.12610.13430.
17、13740.1310.13670.13490.13970.14810.16240.1373UDOF=0.02-(-0.19)0.15720.14720.15260.14130.14580.16690.17920.16280.14220.14670.13480.13160.14990.15320.16390.14430.18930.20660.16110.13280.1340.12950.1270.13750.15510.11820.14370.15140.20.14380.13660.12940.12660.12420.13260.12690.12240.11980.12210.090.160
18、.230.12340.11730.11460.11480.1258-0.19-0.12-0.050.024442-0.33-0.260.14760.144252504846UDOF: Useful DOFThe focus range that shot center & edge are all OKIn left table, UDOF = 0.02-(-0.19)=0.21(um) MP1-0.20.12MP2-0.170.12Common DOF=0.29MP3-0.30.13MP4-0.240.12MP5-0.330.17Common DOF: The focus range tha
19、t all measurement feature are acceptableIn right table, Common DOF = DOF of MP2=0.29(um) Intra-field and Inter-field CDUIntra-field CDU: The CD uniformity of the same shot(field). To get the intra-field CDU, we need same pattern or CD bar in the corner and center of the shot.The intra-field CDU perf
20、ormance relate to not only photo process/machine, but also mask CDUInter-field CDU: The CD uniformity with in wafer. Normally we check more then 10 shot in both wafer center and edge.Inter field CUD mainly relate to the process and Track machine performanceOverlayOverlay(OVL): The layer-to-layer ali
21、gnment performance. P0163_181_179AProduct IDCurrent layerPre layerP1043_156_130X_133YOVL recipeXaXbOVL mark and measurementMore detail about OVL, PLS refer to the hyper-linked file below: photo process OVL introductionADIADI: After Developer Inspection. The OM machine to do this also called ADILitho
22、 process-HMDS690cc550cc660cc1100ccHMDS SUPPLY50cc(to generate HMDS)PR lifting due to HMDS issue H/HL/HL/L(BARC coating)HMDS PR coating SB (TARC coating) WEE Exposure PEB DEV (HB)(OVL) (CD SEM) ADIT=120 CSubstrate surface polarity Change by Chemical treatment(Treatment unit on Coating Truck) OHOHOHOH
23、OHOOHCH3SiCH3CH3CH3SiCH3CH3OHMDSHydrophilicHydrophobicHydrophobicHydrophobicResistResistHMDS Treatment of Substrate Litho process-resist coating(BARC coating)HMDS PR coating SB (TARC coating) WEE Exposure PEB DEV (HB)(OVL) (CD SEM) ADIThinner pre-wetPR dispenseRRC step（EBR）SB(soft bake:Vapor Up of R
24、esist Solvent and Making PR Film.Control of resist components distribution is KeyUniform Non Uniform Non Uniform Wafer Edge Exposure(WEE)Peripheral or edge trace Complete round Line Litho process-Soft back and WEE(BARC coating)HMDS PR coating SB (TARC coating) WEE Exposure PEB DEV (HB)(OVL) (CD SEM)
25、 ADILitho process-Exposure(BARC coating)HMDS PR coating SB (TARC coating) WEE Exposure PEB DEV (HB)(OVL) (CD SEM) ADILitho process-Optics layoutReticleReMa bladesscanningscanningLitho process-Exposure scan(1)one shot on waferTotal dose at waferLitho process- Exposure scan(2)ReticleReMa bladesTotal d
26、ose at waferone shot on waferLitho process- Exposure scan(3)ReticleReMa bladesTotal dose at waferone shot on waferLitho process-Exposure scan(4)ReticleReMa bladesTotal dose at waferone shot on waferLitho process- Exposure scan(5)ReticleReMa bladesTotal dose at waferone shot on waferLitho process-Exp
27、osure scan (6)ReticleReMa bladesTotal dose at waferone shot on waferLitho process-Exposure(7)ReticleReMa bladesTotal dose at waferone shot on waferi-Line Diffusion of PAC 110 C/60s-90s Standard(DUV)Chemical Amplified ResistActivation Energy of deprotection reaction.Deprotection reaction & Acid diffu
28、sionhPAGAcidhPEBDev.Litho process-PEB(BARC coating)HMDS PR coating SB (TARC coating) WEE Exposure PEB DEV (HB)(OVL) (CD SEM) ADILitho process-DeveloperDifferent type DEV nozzleH nozzlePre-dispensePuddleDW rinseSpin dryPuddleDispense DEV solution (BARC coating)HMDS PR coating SB (TARC coating) WEE Ex
29、posure PEB DEV (HB)(OVL) (CD SEM) ADIGood CD performance and defect remove abilityLitho process-DeveloperAdvanced DEV nozzle+Track ScannerLitho process-Inline production machineTel LithiusACT 12DNS ASML TWIBSCAM AT 400CTWINSCAN AT 850C TWINSCAN AT 1150C Canon EX6Litho theory-DOF and ResolutionD.O.F.
30、=K2 X /（NA）Resolution=K1 X /NANA:lens numerical apertureK1, K2:Process Factor :Wave LengthDOF: depth of focus, it means the range of focus shift that pattern can be accepted (CD in spec., profile OK,)objectivelens waferreticlecondenserlens lightsource +1+100-1-1Litho theory-Image formationNA 提高解析度提高
31、解析度Litho theory-Energy/Focus matrix Small Dose BigFEM 寻找寻找Process WindowLitho theory-Photo resist chemical compositionI-lineBase resinPACSolvent(dye)DUVBase resinPAGSolvent(Quencher)OHCH2CH3XSO2OArON2h H2OSO2OArCOOHSO2OArO+N2SO2OArCO WolffrearangementKetene DNQdissolution inhibitor H2OIndenecarboxyl
32、ic aciddissolution promotorNovolac resinh Photo Active CompoundPhoto Acid generatorI-line/DUV光阻对比光阻对比光敏复合物光敏复合物光酸发生剂光酸发生剂OHCH2CH3XSO2OArON2h H2OSO2OArCOOHSO2OArO+N2SO2OArCO WolffrearangementKetene DNQdissolution inhibitor H2OIndenecarboxylic aciddissolution promotorNovolac resinh Litho theory-I-line
33、 resist mechanismI-line光阻：光敏复合物光阻：光敏复合物PAC受光变水溶性受光变水溶性Litho theory- Novolak dissolution rate 因此受光后因此受光后NovolacPAC溶解性大增溶解性大增Litho theory-DUV resist mechanismDUV光阻：光酸发生剂光阻：光酸发生剂PAG受光后产生一个酸，酸和有受光后产生一个酸，酸和有机链上的碳酸醚衍生物反应后再次产生酸，同时有机链水机链上的碳酸醚衍生物反应后再次产生酸，同时有机链水溶性增强溶性增强Lithography ability improvementARC Anti-
34、Reflectivity-CoatingLithography ability improvement- off-axis illuminationQuadrupoleAnnularConventionalIncrease Depth of FocusOAI的使用使的使用使得在同样得在同样NA下一阶光含量下一阶光含量大增，从而增大增，从而增加解析度加解析度1982年美國年美國IBM公司的公司的M. D. Levenson 等人提出等人提出。Conventional Binary chrome-on-glassAlternating phase-shiftLithography ability
35、improvement- PSM 源 自 相 同 光 源 之 兩 光 束源 自 相 同 光 源 之 兩 光 束 ， 若 電 場 振 幅 向 量 間 產 生， 若 電 場 振 幅 向 量 間 產 生 ( 或或 3 、5(2n+1) 等等)之相對相位差之相對相位差，則則形成形成。Lithography ability improvement-PSMPSM利用相邻曝利用相邻曝光区域的干涉，光区域的干涉，使得解析度增加使得解析度增加未经干涉未经干涉效果效果Line-endShorteningPitchEffectCornerRounding-CD approaches exposure wave-le
36、ngth, patterns on the mask no longer printed faithfullyLithography ability improvement- -Different pattern density and environment induce light intensity and information mission after diffraction.Lithography ability improvement- T-TopAmine contamination and N ion (SIN) substrateFootingLithography ab
37、ility improvement- Environment affect除改变环境外，除改变环境外，加加TARC或可解或可解决决T-Top除改变前制程除改变前制程外，加外，加BARC或或可解决可解决FootingStanding wave effect on resist lineSubAirPRIOxideLithography ability improvement-Standing wave effect驻波：因为反射光干涉而成。对于驻波来说，减少反射是最佳方法，驻波：因为反射光干涉而成。对于驻波来说，减少反射是最佳方法，BARC和和TARC都有一定效果都有一定效果BARC absor
38、b the incident light to reduce reflectionWithout BARCWith BARChImprove substrate affect Standing waveSubstrate pattern reflectLithography ability improvement -BARC coatingProcess window(DOF, CD, PR profile, OVL, defect)-Wafer quality:flatness-Film condition:thickness, uniformity, reflectivity-Etch:C
39、D Bias and uniformity, multiple chamber deviation -Design rule and OPC (proximity effect) -Optimize photo condition:resist, recipe, illumination -Machine capability and stability.a.Focus and leveling by dynamic, focus and tilt controlb.OVL matching and calibration, alignment sequence c.CD uniformity
40、 by developer None photo factorPhoto controlLithography ability improvement0.30um0.30um0.25um0.30um0.30um0.30um0.25um0.25um0.25um0.25um0.18um0.18um0.20um0.20um0.18um0.20um0.20um0.50um0.70um0.70um0.50um0.20um0.50umOverlay introductionFor mass production in SMIC, we normally measure Overlay 12 wafers/
41、lot, #10(1wf), or #3(2wf)The OVL spec. comes from integration requirement.The spec. usually gating the max. and min. OVL(single point), or |Mean|+3Sigma OVL. OVL recipe naming is shown as right, it should define the product ID,current layer ID and pre-layer ID P0163_181_179AProduct IDCurrent lay
42、erPre layerP1043_156_130X_133YStandard OVL measurement map as below5 shots / wf4 corners /shotX and Y /cornerTotal collect 40 data / waferOverlay introductionWWSiO2Bare SiMetalPRPRBox in BoxFrame in FrameOverlay introduction-OVL markBar in BarHere are the 3 normal types of OVL mark for Accent OVL ma
43、chine. The Bar-in-bar mark is SMIC standard in Line A XaXbIn right picture,OVL X=(Xa-Xb)/2Overlay introduction-OVL markOVL 10 modelingPhoto PE usually analyses OVL data by 10 modeling. Most of OVL error can be resolved to these modeling, and can be compensated after re-work with these modeling resul
44、t.The OVL error that can not resolved into these modeling we call it residue, it can not be compensated, and residue high Often means measurement error, or the process have some problems.Overlay introduction-OVL mark- OVL modelingShift or translationScaling or expansion Orthogonality1st LayerAA Laye
45、r1st layerAA layer1st LayerAA LayerrotationOverlay introduction- OVL modeling-inter field X&YX&YRotationMag.Asy. MagOverlay introduction- OVL modeling-intra field Asy. Rot.Overlay introduction- OVL modeling and OVL errorR=100mmWhen we have 1ppm wafer expansion, we will get 100 x 1000000 x 1x10-6 =10
46、0nm OVL errorOverlay introduction- OVL modeling and OVL errorWhen we have 1urad shot rotation, we will get (20/2) x 1000000 x 1x10-6 =10nm OVL errorRotationLx=20mmPhoto Trouble shootingCD NGOVL NGDefocusOther issueSampleCD NGCD jump:Energy shift(due to APC or MO)? CD SEM measurement error? SEM PM? S
47、EM recipe modified? SEM operator changed? Scanner focus shift? Energy sensor shift?PR batch change? DEV batch change? Substrate film abnormal?CD lot to lot variation:Energy variation? CD SEM measurement error? SEM to SEM variation? Different SEM operator?Photo process window no enough? Substrate fil
48、m abnormal?CD with in lot variation:Lens heating(trend up or tend down)? Cooling plate issue/Coater issue/Soft bake issue/hard bake issue/BARC issue(By two)? PEB issue/DEV issue(by four)?Substrate film abnormal?Photo Trouble shootingCD NGCD with in wafer variation:Center edge difference: Coating un-
49、uniform issue?Half to half difference: hot/cooling plate (arm)position issue? Substrate film abnormal?CD with in shot variation:Mask issue? Lens slit uniformity issue?Scan speed un-uniform issue?Leveling NG(tilt)issue?course the focus NGbignormalHot platewaferspotPhoto Trouble shootingOVL NGOVL jump
50、(no residue high):APC correction issue(due to feed wrong data feed back or MO)? Use new version mask?OVL machine condition jump(after PM)? OVL recipe modified? Scanner OM condition jump(after PM)? Pre-process change or tool change(specially check anneal/CMP process)?OVL lot to lot variation:APC corr