Effect of PAG Location on Resists for Next Generation Lithographies ber Research Group Materials Science & Engineering Ithaca, NY 14853
Development Trends in Microlithography 10 Contact Printer Architectures N X H 3 C N H 3 C Resolution (µm) 1.0 0.1 Cyclized Rubber 436nm 365nm 248nm DNQ - Novolak HS Copolymers 193nm H H H H Hydrocarbon Polymers 75 85 95 05 Year H
Positive Chemically Amplified Photoresist Chemistry hv H + H Aqueous Base Dissolution H PAG H 0.40µm ( ) 4 N + H - 0.12µm
Photoacid Generators - PAGs I h? Homolysis I + RS 3 RS 3 XH Radical Abstraction / Protonation X I + RS 3 H Dissociation I H + RS 3
Rutherford Backscattering? Depth resolution ~ 200 A Res is t Lay er? RBS spectrum contains information about target s? mass? concentration? depth profile? Most photoacid generators (PAGs) have a self-label such as Sb, I, etc. 4 ++ He PAG Ion Beam E (MeV) 0 E 1 E 2 Energy Sensitive Detector E M < M 1 2 E 1 2
Diffusion of PAG and Photogenerated Acid Concentration (a.u.) 150 125 100 75 50 25 0 PAG (1) Exposed SbPAG - experimental Exposed SbPAG - simulated Unexposed SbPAG - experimental Unexposed SbPAG - simulated Photogenerated acid (2) 0 5000 10000 15000 20000 25000 Thickness (Â) 120 o C/60s S + Sb F 6 - (1) h?,? H Sb F 6 (2)
Photoacid Generator (PAG) Distribution = PAG = Matrix H Br S 2 CF 2 CF 2 CF 2 CF 3 Uneven distribution of PAG Si wafer T-topping Closure Footing
Effect of Block Copolymers As Additives THPMA-b-IBMA with and without IBMA-b-MMA additive C C 60 50 THPMA-b-IBMA with 40 30 wafer C C MMA-b-IBMA 20 with bcp without bcp 10 0-0.2 0 0.2 0.4 0.6 0.8 1 1.2 Normalized film thickness
Block Copolymers as Additives CH 2 CH C 2 CH C 2 C a b c C C C IBM zero thinning resist H 3 C C H MMA-tBMA-MAA with 2 wt% MMA-b-IBMA 5800 A thick films ; PAB -140C/60s PEB - 140C/60s ; Dev. - 0.05 TMAH
Effect of Block Copolymer Additives - SIMS Measurements 1000 Carbon Photoacid generator Deuterium of Block Copolymer Additive I CF 3 (CF 2 ) 3 S 3 Concentration (a.u.) Iodine of PAG with additive Iodine of PAG without additive (5 wt%) CD 3 CD C b 2 CH 2 C a b C C CD 3 100 0 500 1000 1500 2000 2500 3000 3500 4000 4500 5000 Air-polymer interface Thickness (Å) substrate-polymer interface Block copolymer additive 2 wt%
Polymers for Chemically Amplified Photoresists H H + H pk a = 9-10 H + H pk a = 9-10 / pk a = 4-5 H H H + pk a = 4-5 H H H + pk a = 4-5 / Anhydride H
Labeling of Photoacid Generators for RBS Self Labeled No Label S S SbF 6 RS 3 CF 3 S 3 I N S 2 CF 3 Heavy Atoms: Sb (51), As (75), Br (79), I (127) Light Atoms: C (12), N (14), (16), F (18), S (32)
Design of Labeled PAGs for RBS Study Iodonium Polar PAGs Non Polar Sulfonate Esters I-1 I CF 3 S 3 Br-1 Br S 2 I-2 I CF 3 (CF2) 3 S 3 Br-2 Br S 2 CH 2 CH 2 CH 2 CH 2 CH 2 CH 2 CH 2 I-3 I CF 3 (CF 2 ) 7 S 3 Br-3 Br S 2 CF 2 CF 2 CF 2 CF 3 H 3 C I-4 I S 3 Br-4 Br S 2 CF 2 CF 2 CF 2 CF 2 CF 2 CF 2 CF 2 CF 3 I - Labeled Br - Labeled
Design of Non-Polar Sulfonate Ester PAGs Moiety to Investigate Structural Effects Br S 2 RBS Label Steric Hindeance for Thermal Stability Thermally Stable in Phenolic and Methacrylate Matrices Photogenerates acid via Blocked Photo-Fries
Model Photoresist Matrices 248 nm 193 nm H H H 70/30 57/20/23 Hydrophilic Hydrophobic
Distribution of Polar Ionic PAGs in Poly(4-Hydroxystyrene) I CF 3 S 3 I CF 3 (CF2) 3 S 3 Si Air H I CF 3 (CF 2 ) 7 S 3 H 3 C I S 3 S I The distribution of Iodonium PAGs is uniform through the depth of the PHS film independent of counter ion
Distribution of Polar Ionic PAGs in 193 nm Acrylic Matrices 0.003 0.0025 I CF 3 S 3 0.002 0.0015 I CF 3 (CF2) 3 S 3 0.001 CF3S3 0.0005 CF3(CF2)3S3 CF3(CF2)7S3 0-0.2 0 0.2 0.4 0.6 0.8 1 Normalized film thickness I CF 3 (CF 2 ) 7 S 3 Degree of segregation is dependent upon lenght of fluoronated counter ion
RBS Spectra of N-xy Sulfonate in PHS N S 2 CF 3 Si Air H S Collaboration with G. Barclay, Shipley Heavy Atoms: Sb (51), As (75), Br (79), I (127) Light Atoms: C (12), N (14), (16), F (18), S (32)
RBS Spectra of Iodonium Triflate in PHS CF 3 S 3 I Si Air H Si Air
Distribution of Non-Polar PAGs in PHS Copolymers Uniform Distribution Si Air Br-1 Br-2 Br Br S 2 S 2 CH 2 CH 2 CH 2 CH 2 CH 2 CH 2 CH 2 H 70/30 Non-uniform Distribution Br-3 Br S 2 CF 2 CF 2 CF 2 CF 3 Phase Separation - Insoluble in Matrix Br-4 Br S 2 CF 2 CF 2 CF 2 CF 2 CF 2 CF 2 CF 2 CF 3
Distribution of Non-Polar PAGs in Model 193 Matrices PAG concentration, atomic % 0.002 0.0015 0.001 0.0005 0 wafer c8h17 c4f9 c8f17 air Br S 2 (CH 2 ) 3 Br S 2 (CF 2 ) 3 CF 3 Br S 2 (CF 2 ) 7 CF 3 c8h17 c4f9 c8f17-0.2 0 0.2 0.4 0.6 0.8 1 1.2 Normalized film thickness H Matrix
Distribution of Non-Polar PAGs in Model 193 Matrices Br-4 Br S 2 CF 2 CF 2 CF 2 CF 2 CF 2 CF 2 CF 2 CF 3 Si Air H S I Matrix
Comparison of PAG Distribution Different Resist Matrices 0.0025 0.002 PHS-tBA IBMA-MMA-tBMA Non Polar Sulfonate PAG Br S 2 (CF 2 ) 3 CF 3 0.0015 0.001 H 0.0005 0-0.2 0 0.2 0.4 0.6 0.8 1 1.2 H Normalized film thickness
Dissolution Behavior Incident Light Photoresist Substrate H 70/30 1000 1.2 10 4 900 1 10 4 800 8000 700 6000 600 4000 500 2000 400 0 0 50 100 150 200 250 300 350 Time (A sec) 0 50 100 150 200 250 300 350 Time (Sec)
Dissolution Behavior of Matrix Containing Model PAG H 3 C F 3 CF 2 CF 2 CF 2 C 2 S H 3 C Br H 70/30 1100 8000 1000 900 7000 6000 5000 4000 800 3000 700 2000 1000 600 0 0 1000 2000 3000 4000 5000 Time (sec) 0 1000 2000 3000 4000 5000 Time (sec)