UV2Litho Usable Vacuum Ultra Violet Lithography

Transcription

1 UV2Litho Usable Vacuum Ultra Violet Lithography A.M. Goethals, R. Jonckheere, F. Van Roey, Jan Hermans, A. Eliat, K. Ronse (IMEC) P. Wong (ASML) P. Zandbergen (Philips) M. Vasconi, E. Severgnini (STMicroelectronics S.r.l) W. Henke, C. Hohle (Infineon) D. Henry, Ph. Thony, L. Markey (STMicroelectronics SA) P. Schiavone, D. Fuard (CNRS-LTM) 1

2 Project objectives Accelerate the development of 157nm manufacturable lithography process for the 70nm node Key objectives: Provide feed-back to resist and mask suppliers to guide their development for 157nm Provide metrology solutions for the 70nm node Provide resist solutions for 157nm production scanner (scanner as being developed in FLUOR*) Demonstrate 157nm resist solutions on the critical layers for the 70nm node * See Poster FLUOR : Frontline Lithography Using Optical Refraction 2

3 Work Packages and interactions WP1 User requirements WP2 Resist screening Project structure WP6 Lithography Modeling WP5 Reticle printability WP4 Metrology solutions WP3 Process demonstration Project timing September 1, August 31,

4 Consortium IMEC (Belgium) ASM Lithography (The Netherlands) Philips Innovations Technology Solutions (PITS) (Belgium) ST Microelectronics SA (France) Infineon Technologies AG (Germany) Laboratoire des Technologies de la Microélectronique CNRS (CNRS-LTM) (France) ST Microelectronics S.r.l. (Italy) 4

5 Status of the 157nm infrastructure The program will be carried out using a 157nm lithography infrastructure to be installed at IMEC consisting of : 0.75 NA MSVII engineering system (Dec 2002) TEL Clean Track ACT8 (under installation) CD metrology : KLA8250XR (available) characterization of wafers, reticles UVO reticle cleaner (Sept 2002) SOPRA PUV spectroscopic ellipsometer N2 purge box with load lock (Sept 2002) Measurement of wafers and reticles 5

6 Micrascan VII engineering system The world s first 157nm full field scanner Properties : Parameter Requirements Wafer Size 200/300mm Reticle Size 6 Reduction Ratio 4:1 Projection Optics NA (variable) Partial Coherence (variable) Quad and Annular Options available Field Size 26x34 mm Runrate (200 mm wafers) 40 wafers/hour Compromises for delivery in Q reduced throughput (25wph) to avoid lens heating effects off-line VUV reticle cleaner field size : 20mm x 34mm (early optics quality) 200mm only configuration 6

7 WP 2 : Resist screening Goal Come up with a suitable tool set-up and qualification resist for the ASML AT1600 (interaction with FLUOR project)* Identify 157 nm resist solutions for manufacturable processing of critical layers for 70nm technology node Approach Resist screening from commercial resist suppliers Resist development : CARL process (Infineon) Partners involved : ASML, IMEC, STM, Philips * See Poster FLUOR : Frontline Lithography Using Optical Refraction 7

8 WP2 : Program phases Phase I (Q Q4 2002) Resist screening on micro-steppers at Sematech and at Selete (0.60 NA and 0.85 NA) Selection of a qualification resist for the ASML MSVII Phase II (Q Q2 2004) Screening and resist benchmarking on full field scanner : ASML MSVII (0.75NA) Selection and optimization of a resist process for the ASML AT1600 full field scanner Phase III (Q ) Screening on high NA full field scanner 8

9 Status of resist screening on microsteppers Screening >30 resist samples evaluated in the last year including UTR resists, Si based resist and F-polymer resists Evaluation with NA 0.6 and NA0.85 using BIM and PSM Typical performance on 0.60 NA stepper Ultimate resolution BIM : 100nm 1:1, 90nm 1:1.5, 100nm iso PSM : 80 nm L/S Processing latitudes BIM 110nm 1:1, DOF= um, EL=3-5% 110nm 1:1.5, DOF=0.4um, EL=5% 110nm 1:1.5, DOF=0.4um, EL=10-12% PSM 90nm 1:1, DOF= um, EL=5% 60nm iso, DOF= um, EL= % Sensitivity BIM : 19 to 28 mj/cm 2 (dose to size for 110 1:1) PSM : 25 to 67 mj/cm 2 (dose to size for 90 1:1) 9

10 Progress in resist performance Ultra thin resist and 1 st semi-transparent resists in 110nm thick resist on Silicon (=reflective) substrate Q2, 2001 Q3, nm L/S, silicon 90nm L/S, silicon UTR resist 67nm thick SLR resist 112nm thick Resist with higher transparency in 110 nm thick resist on antireflective substrates 90nm L/S, SiON 90nm L/S, organic ARC SLR resist (siloxane) 112nm thick Resist R Q1, nm L/S, organic ARC SLR resist (F-polymer) 110nm thick Resist 2002-M 60nm IL, organic ARC 50nm IL Exposure courtesy of Sematech, 0.60 NA, PSM10

11 Advanced transparent resist status Q Organic ARC 150nm 200nm 90nm L/S E = 31.0 mj/cm 2 60nm IL 90nm L/S E = 32.5 mj/cm 2 60nm IL SiON 200nm 90nm L/S E = 40.0 mj/cm 2 60nm IL Exposure courtesy of Sematech, 0.60 NA, PSM 11

12 Results on 0.85 NA microstepper 70nm L/S 65nm L/S 40nm 1:5 L/S Process window for 65nm L/S 12 Doc: XP1664_65nm : XP1664_65 dense Resist Thickness 1100 Å Substrate: organic ARC 0.85 NA, PSM Depth of Focus Exposure courtesy of Selete, 0.85 NA, PSM 12

13 Trend in etch resistance Relative etch rate in CF 4 plasma (Kr resist as reference) as a function of resist absorbance Relative etch rate Absorbance [1/um] 13

14 SLR resist progress summary Significant improvement in resist performance in the last half year Resists with higher transparency are becoming available allowing printing in thick (up to 200nm) layers on anti-reflective substrates Results on the 0.85 NA system at Selete demonstrated 65nm L/S and 40 nm Iso lines Critical issues which need for improvement : Etch resistance LER Sensitivity to contamination Further improvement in substrate compatibility (SiON) 14

15 Benefits of CARL Shrink Technology for future 157nm litho nodes (Chemical Amplification of Resist Lines) exposure + PEB wet development wet silylation dry development Thin Si-free resist Transmission Outgassing Pattern collapse Shrink / chemical bias Contact holes LER Bottom layer Etch resistance Wet silylation: chemical biasing (crosslinking) of developed resist polymer via treatment with reactive siloxane (up to 30wt.% Si-incorporation) CARL ultrathin bilayer resist addresses critical issues of 157nm litho Need for chemical modification to reach transmission goal of < 5µm -1 15

16 O CH O O 3 CH 2 m n O H H O α 157 = 6,5µm -1 Results CARL Decreased absorbance via fluorination of anhydride CH O 3 O O CH 2 m O H O n CF 3 α 157 = 5,3µm nm 110 nm 120 nm Process conditions: 5wt.% PAG, 70nm FT on Si, PAB 110 C/90s, PEB 110 C/90s Exposure: Exitec 157nm Microstepper, NA=0.6, σ = 0.3, Mask: alt.psm Development: 2,38% TMAH (30s) Printing of 110nm l/s (1:1) demonstrated, resolution limited due to T-topping Vertical film thickness increase after wet silylation reaction of more than 20% Outlook: Polymer fine tuning (α 157, T g, polarity, adhesion... ) 16

17 WP4: Study of Metrology Issues Goal: Assessment of metrology options for 157nm litho technique targeted on 65nm design rules Approach: Investigation of the most suitable measuring techniques (CD-SEM, CD-Scatterometry, Combo options) Development of measurement procedures Partners ST Microelectronics S.r.l., ST Microelectronics SA 17

18 WP4: Study of Metrology Issues CD-SEM benchmarking 157nm demo wafers (L&S and CH) shipped to 3 different supplier sites: Supplier A : task completed, results delivered Supplier B : task completed, results due Supplier C : task in progress Issues investigated: SEM ultimate resolution Single-tool precision Line edge roughness algorithm Interaction with target Pattern visibility 18

19 WP4: Study of Metrology Issues CD-Scatterometry benchmarking EBDW demo wafers shipped to 6 different supplier sites All the tasks have been completed First information gathered on tools capability and suppliers reliability Tentative specifications defined with respect to the roadmap timeframe Tool selected for on-site evaluation purposes 19

20 WP4: Study of Metrology Issues Combo tool option The combination of 2 or more techniques in the same piece of equipment Among the possible solutions, up to now just the FIB+SEM machine is available on the market FIB milling & SEM X-section measurement applications on 157nm resist are being developed on-site 20

21 WP4: Study of Metrology Issues Main findings Evaluation of the classes of tools for CD measurements Summary of results: SEM Scatterometry AFM Holography Combo Timing Precision Resolution Interaction Universality LEGEND: Higher performance is indicated by ++, neutral by 0, lower by -- ; in the first line reliable system availability is indicated by ++, first commercial tools available on time by 0, β-tool barely available or not available on time by -- 21

22 WP4: Study of Metrology Issues Main findings (cont d) Tool benchmarking first results: 157nm Wafers 65nm Node Wafers SEM Scatterometry Combo (SEM+FIB) Precision and resolution sufficient; interaction with target heavy (tungsten No problems with 157nm deposition and target cut materials required); cutting procedure to be optimized; target profile data easily available Precision and resolution sufficient; interaction with target better than forecast (CD local variation lower than in 193nm materials) Precision to be improved and verified on more substrates Precision to be improved and verified on more substrates; major upgrades required for hole layers In progress 22

23 WP4: Study of Metrology Issues Metrology procedure development CD-SEM measurements: Precision as well as interaction with the target to be verified on more substrates FIB milling: Cutting procedure to be optimized aimed at obtaining reliable target profile data CD-Scatterometry measurements: Application study in progress on-site, for performance and profiling capability validation under different conditions 23

24 WP5: Reticle printability Goal: Assure timely available high quality 157nm reticles for the ASML MSVII and AT1600 Approach/Tasks: Test design Reticle specifications Reticle manufacturing Reticle characterization Reticle quality printability Reticle handling Partners IMEC, Philips 24

25 WP5 : Reticle printability Requested feedback to 5 mask shops worldwide about their capability for 157nm reticles, based on a reticle requirement roadmap Node BIM Aggr.OPC EPSM AAPSM BIM Aggr.OPC EPSM AAPSM Q1 Q2 Q3 Q CD nm FF-4X (MSVII) nm FF-4X (AT1600) Q1 Q2 Q3 Q Q1 Q2 Q3 Q Q1 Q2 Q3 Q Q1 Q2 Q

26 WP5 : Reticle printability detailed reticle specifications <100nm, for MSVII and preliminary specs for AT1600 Binary Illumination Masks (BIM) (4X Reticles; High End) Technology (nm) Optical Proximity Correction (OPC) Critical dimension (Additional (CD, nm, on top of those for BIM) Feature size (4X Reticles; High End) Space Dense (100 Embedded %) [S100] Attenuated PSM 100(EAPSM) Technology (nm) Semi-dense (~130 (Additional %) [S130] specifications 130 on top of those 110 for BIM) 85 Minimum feature size (~65 %, isolated) (4X Reticles; High End) OPC feature size (nm) Minimum pitch (200 %) High aggressiveness (35 %) [OPCHA] Technology (nm) Alternating Aperture PSM (AAPSM) 100 CD MTT OPCHA (nm, ±, 10 %) (Additional specifications 14 on top of those 12for B Feature size Shifter control(4x Reticles; 400High End) Space Moderate aggressiveness (50 %) [OPCMA] EAPSM transmission (± %) Dense MTT (100 OPCMA %) (nm, ±, 10 %) [S100] Target Technology (nm) Semi-dense (~130 %) [S130] % [TR6] 6 Minimum feature Low size aggressiveness (~65 %, isolated) (75 %) [OPCLA] Minimum pitch (200 MTT %) OPCLA (nm, ±, 10 %) AAPSM 9 % chrome 800 level [TR9] MTT (% of the Target) 5 CD control Uniformity (% of the Target) 4 OPC present but not specified Mask technology [OPCNO] code (different * from BIM) * CD mean-to-target (MTT, nm, ±) EAPSM Phase Reticle (± degree type (deg)) /AAPSM Target 18026

27 WP5 : Reticle printability 157nm mask substrates present blank specs considered for MSVII: birefringence <1nm/cm (polarized!!), still specified at 633nm and unknown size at 157nm!! flatness <0.5um already available from AGC Preparing for first MSVII printing performance characterization reticle Preparing for VUV lamp cleaning Received first 157nm masks and substrates only Sopra PUV tool will accommodate reticle measurements (installation 9/2002) VUV lamp cleaning unit will be installed 9/2002 Analyser arm Goniometer Mapping stage Polariser arm + spectrometer 27

28 WP6: Lithography modeling Participant : CNRS-LTM Objectives Assess different resist models and calibrate according to experimental data of WP2 and WP3 Evaluate through simulation the performance and limits of 157nm lithography, compare with alternative solution if available (e.g. 193nm+PSM for the 70nm node). Evaluate the relevance of using scalar high NA models. Determine the influence of the polarization on the aerial image through the use of rigorous electromagnetic models. 28

29 WP6: Lithography modeling Assessment + calibration of resist models Data fitting: Use a fitting formula that relies on as much physical basis as possible Perform a global fit of the Bossung curve family Isofocal CD, focus offset, are drawn directly from the fit CD (µm) Defocus (µm) 29

30 Model assessment: WP6: Lithography modeling aerial image, diffused aerial image, aerial image + variable diffusion, lumped parameter 20.00% 18.00% 16.00% 14.00% Aerial image only Aerial image + gaussian noise model Aerial image only + variable gaussian noise model Lumped Parameters 12.00% 10.00% 8.00% 6.00% 4.00% 2.00% 0.00% Iso Iso σ=0.6 σ=0.85 Mean prediction errors: 30

31 WP6: Lithography modeling Results for contact JSR M79Y resist 450nm thick+ 57nm DUV30 Contacts 200nm (pitch 320 and 640nm) and 220nm (pitch 320 and 720nm) CD (µm) CD (µm) CD (µm) Defocus (µm) defocus (µm) Defocus (µm) With best gaussian noise (26nm) mean CD error =4% 31

32 WP6: Lithography modeling Conclusion Aerial image + gaussian noise is a simple and efficient model valid for lines and contacts at various wavelength (CD error 2% to 5%) Variable gaussian noise does not improve the results significantly Lumped parameters provides poor prediction accuracy 32

33 Acknowledgements International Sematech K. Turnquest, V. Graffenberg, M. Rodriguez, S. Patel, G. Rich, D. Miller Selete T. Itani, O. Yamabe, S. Miyoshi, T. Suganaga, T Furukawa IMEC S. Beckx, S. Locorontondo Infineon N. Heusinger, M. Kern, B. Ruppenstein,E. Richter, W.D. Domke, K. Elian 33