New materials for surface energy control of 193 nm photoresists

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Wilfred Mitchell
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Phil Brock, Ratnam Sooriyakumaran, Hoa Truong, Robert

1 New materials for surface energy control of 193 nm photoresists Dan Sanders, Linda Sundberg, Hiroshi Ito, Phil Brock, Ratnam Sooriyakumaran, Hoa Truong, Robert Allen IBM Almaden Research Center, San Jose, CA IBM Corporation

2 193 nm resist No topcoat Stain left by evaporated water droplet Reducing defectivity via surface engineering Film pulling velocity [mm/s] Transition region ~65 Defects [1/cm 2 ] Fast Scanning θ static,receding [ ] Nakagawa et al. Proc. SPIE, Shedd et al. Proc. SPIE, Examples of defects Wallraff et al. Proc. SPIE,

3 Beyond conventional topcoats Current base-soluble topcoat technology Topcoat Wafer Topcoat-free resists Graded topcoat materials Surfaces for high index immersion 3

SPIE 2007: Topcoat-free resists show good performance AM2073 / TCX014

Exposure Latitude (%) 15 10 5 Exposure Latitude (%) 15 10 5 Exposure

4 SPIE 2007: Topcoat-free resists show good performance AM2073 / TCX014 P180S90 87nm ± 13nm (ASML 1150i) att. PSM reticle, 0.75NA, annular (0.59 inner outer sigma) AM2073 / Additive 3B AM2073 / Additive 3D Exposure Latitude (%) Exposure Latitude (%) Exposure Latitude (%) DF (µm) PAG leaching 2.49 ppb DF (µm) DF (µm) 3.53 ppb 7.32 ppb 4

5 IBM Almaden Research Center Additive structure strongly impacts surface enrichment JSR AR1682J Additive A Additive B Additive C Additive D JSR B Additive A Additive B Additive C Additive D % Additive % Additive Depth [nm] Depth [nm] R acid-labile n n 5 F 3 C CF 3 R acid-labile F 3 C CF 3 H F 3 C CF 3 H F 3 C CF 3 H A B C D

6 Film structure largely formed during spin-casting 100 AR 1682J w/ Additive E w/ Additive F Normalized PAG Leaching [%] % 16.6% 15.6% % 0.88% No Bake 110 C 130 C PAB Temperature 1.93% Effect of PAB on leaching is minor Consistent across different additives 6

7 Breaking performance barriers with graded topcoats Current base-soluble topcoat technology Topcoat Wafer Topcoat-free resists Graded topcoat materials Surfaces for high index immersion 7

8 Graded topcoats via polymer blending + Blend Deposit Use surface segregation to direct polymers to appropriate interfaces High contact angles (θ s,r 70 ) Good profile control Same process cost as conventional topcoat Can tune properties more independently to break the limiting materials property trade-offs Fluorine rich Acid rich Spin cast Top polymer Fluid contact angles Surface segregation Dissolution rate Bottom polymer Dissolution rate Acid content interactions Refractive index 8

9 Blending typical topcoat polymers gives only average properties Fluorinated copolymer surface energy control x F 3 C CF 3 H R f Surface activity High contact angles Acidic group for dissolution y + Sulfonic acid copolymer profile control x F 3 C CF 3 H HN S y H Profile control Khojasteh et al. Proc. SPIE, Homogeneous RCA = 63.2 Δ = -2.5 Thin surface layer Segregation to both interfaces Δ is the difference between observed RCA and average RCA of components 9

10 Materials design produces graded topcoats Fluorinated copolymer surface energy control Sulfonic acid terpolymer profile control x F 3 C CF 3 H R f Surface activity High contact angles Acidic group for dissolution y + RCA = 69.4 RCA = 42.1 R acidic x Dissolution R S H Profile control y R polarity z T g /polarity Homogeneous Thin surface layer Segregation to both interfaces RCA = 67.1 Δ = Film distribution: SIMS, XPS, ellipsometry, QCM, contact angles, contrast curves 10

Contrast curves suggest segregated film structure

200 0 Topcoat: None (1692J) Top polymer only Bottom

Blended polymers 0 2 4 6 8 10 12 14 Dose (mj/cm 2 )

11 Contrast curves suggest segregated film structure 1200 Top polymer only 1000 Thickness (nm) Topcoat: None (1692J) Top polymer only Bottom polymer only Blended polymers Bottom polymer only Blended polymers Dose (mj/cm 2 ) Control TCX-014 (30 nm) Graded topcoat Bottom polymer only 11

12 Re-engineering of acidic bottom polymer resolves issues Reference TCX-014 (30 nm) Fluorine-free bottom material Alternative sulfonic acid group 4.77 mj 5.76 mj 5.27 mj RCA: 55.6 Commercial topcoat RCA: 59.2 RCA: 61.4 Graded topcoat 12 : JSR AR1682J, 45 nm hp, 193 nm water immersion interference lithography

13 Graded topcoat summary Possible to achieve high receding contact angles Film structure measured by XPS, SIMS, etc. Thin surface wetting layers and homogeneous interior Graded topcoat Haven t yet exceeded performance of commercial topcoats Challenge to ensure optimal resist interaction Fluorine-free bottom polymers may allow cost reduction Possible anti-reflection benefits. Range Best RCA Sample Top polymer Bottom polymer (AR1682J) RI TCX-014 TCX-041 Conventional topcoats Additive-based topcoat-free resists are superior route to break trade-offs Can use acid-labile protecting groups 13

14 Topcoat-free resists for high index immersion Current base-soluble topcoat technology Topcoat Wafer Topcoat-free resists Graded topcoat materials Surfaces for high index immersion 14

15 Lower contact angles of high index fluids JSR AR1682J Receding contact angle Water JSR HIL-001 Bicyclohexyl 1682J Daikin RP Asahi FGC-400 JSR TCX-014 TK TSP-3A Initially reported at 2006 IEEE Lithography workshop and 3 rd International Symposium on Immersion Lithography Water JSR HIL-001 JSR TCX-014 TK TSP-3A JSR AR1682J JSR TCX-014 TK TSP-3A

16 rganic immersion fluids film pull at low velocities Collaboration with: P. Harder, S. Schuetter, T. Shedd (University of Wisconsin) Film Pulling Velocity [mm/s] TK TSP-3A JSR TCX υ crit υ Water Decane trans-decalin Cyclooctane Bicyclohexyl ( m m υ + ) = υ fp γ μ in 3 fp θ s,r Film pulling velocity (on TSP-3A) 850 mm/s 150 mm/s 120 mm/s 130 mm/s 100 mm/s 1/ m Static Receding Contact Angle 16 REFLECTIN FILM PULL STREAKS WAFER Sanders et al. 3 rd Int. Symp. Immersion Lithography (2006).

17 Fluid handling options for high index immersion (NA 1.55+) Local delivery wafer dry Allowed film pulling partially wet Submersed/Pool wafer wet Tool Conventional showerhead Conventional showerhead New delivery method Process Conventional New fluid removal process New fluid removal process Materials Topcoats w/ RCAs > 120 Inert resist or topcoat Inert resist or topcoat Contact angle targets unknown Higher is presumed better 17

18 PAG extraction and stain morphology different than water Normalized PAG Extraction Low PAG extraction into high index fluids Fluid Water JSR HIL J 100 ND 1682J + TCX ND 1682J + TSP-3A ND ND AR1682J AR1682J + TCX-014 AR1682J + TSP-3A Water Surface controls Stain morphology JSR HIL Sanders et al IEEE Lithography Workshop

Improved additives for high index immersion

Additive F Additive G JSR TCX-014 Additive H

(HIL-001) AR1682J w/ Additive-only topcoat or

19 Improved additives for high index immersion Application Water High index Additive None Additive F Additive G JSR TCX-014 Additive H Additive I TK TSP-3A Receding contact angle (HIL-001) AR1682J w/ Additive-only topcoat or additive - <2 Dissolves < (smaller drop volume) JSR AR1682J w/ Additive G JSR TCX-014 w/ Additive H w/ Additive I TK TSP-3A 19

Fluid: JSR HIL-001 Materials designed for

20 Additives compatible with high index immersion achieved 193 nm interference immersion lithography (45 nm hp) : JSR AR1682J (80 nm) on ARC29a (780 Å) Immersion Fluid: JSR HIL-001 Materials designed for water Materials designed for high index TCX-014 (25 nm) Additive F Additive H Additive I mj mj mj mj RCA: 24.0 RCA: <2 RCA: 42.1 RCA:

Additives optimized for fluid interaction not PAG

nm) Additive H Water immersion TCX-014 (25 nm) Additive H

21 Additives optimized for fluid interaction not PAG leaching High index immersion (JSR HIL-001) TCX-014 (25 nm) Additive H Water immersion TCX-014 (25 nm) Additive H Sample Water Cyclooctane Bicyclohexyl AR1682J (absolute) 28.5 ppb 1.25 ppb 0.62 ppb AR1682J (normalized) AR1682J w/ TCX-014 AR1682J w/additive H 100% 5.8% 156% 100% ND ND 100% ND ND 21

22 New materials for immersion lithography Conventional Topcoats Graded Topcoat Topcoat-free (water) Topcoat-free (high index) Wafer RCA (water) TCX-014: 55.6 TCX-041: (HIL-001) Graded topcoats show some potential for improved performance/reduced cost Additive-based topcoat-free resists are superior way to break trade-offs Can use acid-labile protecting groups Additive structure strongly influences surface segregation & performance Designed additives specifically for high index immersion Moderate RCAs with high index fluids Tailor additives differently than for water-based immersion Can tune RI with more freedom than with a topcoat 22

23 Acknowledgements IBM Dolores Miller (IBM-ARC) for XPS Vaughn Deline (IBM-ARC) for SIMS Dario Goldfarb (IBM-YKT) for ellipsometry Peggy Lawson and Rex Chen (IBM-EFK) for 1150i imaging University of Wisconsin Paul Harder, Amy Stoikes, Scott Schuetter, and Tim Shedd JSR and JSR Micro. Photoresists, TCX-014 topcoat, and HIL-001 Mark Slezak Central Glass Selected monomers and polymers TK, Daikin, Asahi Glass 23

Lithography options for the 32nm half pitch node. imec

Lithography options for the 32nm half pitch node imec 2006 1 Lithography options for the 32nm half pitch node Luc Van den hove and Kurt Ronse ITRS roadmap:32 nm half pitch requirement Product Half-Pitch,