Directed Self-assembly of Topcoat-free Polycarbonate-containing High-χ Block Copolymers, Kristin Schmidt, Gabriela Alva, Noel Arellano, Teddie Magbitang, Anindarupa Chunder, Melia Tjio, Elizabeth Lofano, Joy Cheng and Daniel P. Sanders 2015 DSA Symposium Leuven, Belgium ct. 27 th 2015
Background: Motivation for High-χ BCPs PS-b-PMMA is the most promising candidate as Generation 1 material for DSA 15k-15k PS-b-PMMA 14k-14k PS-b-PMMA Pitch (Lo) ~ 20 nm 500 nm Higher-χ BCPs needed for sub-20 nm pitch resolution 2 Reduce pitch by increasing χ ~ / / = 10.5 Potential benefits of High-χ BCPs Smaller pitch Lower LER Higher etch-selectivity
Materials Development for Sub-20 nm Pitch Patterning New Block Copolymer Synthesis rientation Control Strategy underlayer Si substrate Spin coat BCP solution Thermal anneal underlayer Si substrate R R PLA PTMC R rganocatalytic RP at IBM -Jim Hedrick and team R 1 H N H PMD R 2 H H R 1 N H R 2 R R Si PVL R H Si Si PTMCS H Si H Si Si Si R R R R Si Si Si H PDMS PCL PE PBL H H H Desired Characteristics Perpendicular orientation by short thermal annealing Top-coat free ab compatible processing / solvents Compatible with existing DSA schemes 3 Chem. Rev., 2007, 107 (12), pp 5813 5840
utline Phase-selective, surface active polymer (SAP) as additives for top orientation control of polycarbonate-containing BCPs Design rules for making highly efficient SAP additives SAP molecular weight & PDI DSA compatible SAP additives Generation II high- χ materials towards integration friendly materials Polystyrene-b-Polytrimethylene Carbonate Gen I BCP 1. rganocatalyst + 2. TEA, AcCl PS-b-PTMC 4
Previous Results from Photopolymer 2015 Conference Development of High Purity PS-b-PTMC BCP Mn GPC = 21.5k PDI = 1.02 BCP Mn NMR = 6.6k-7.5k PS-H Macroinitiator Mn = 6.6k, PDI ~ 1.04 Carbonate-based Underlayer Materials Sty = 62 mol%, 0.5 Lo islands Neutral Underlayer Surface-active Additives for Top rientation Control? Carbonate-based Neutral UL Coat BCP + Additive HA-materials as Phase-selective, Surface-active Polymer (SAP) Additives Neutral UL Anneal Surface active 5 Neutral UL Hydrogen bonding w/ Polycarbonates
HA Materials as Surface Active Polymer (SAP) Additives ormulation: Neutral Underlayer ormulation= BCP + 10% PHA-Sty Polycarbonate Containing BCP + P(HA-Sty) BCP+ P(HA-Sty) Neutral UL + solvent 3 C H C 3 Baking Pitch ~ 19 nm 100 nm Neutral UL PS-PTMC 6.2k -7.7k(Vf ~0.5) + 10% P(HA-Sty), Bake @ 140 C/5 min UL = Neutral orientation of lamellae high-χ BCP by simple coat and bake Low annealing temperatures & fab-compatible processing 6 What are the design rules for developing highly-efficient SAP additives?
Effect of Additive Molecular Weight on Self Assembly SAP Additive: Poly(HA-Styrene) BCP: PS-b-PTMC SAP amount = 5 wt% w.r.t BCP BCP Mn = 6.6k-b-7.7k, VfPTMC~ 0.49 BCP Pitch ~ 19 nm 3 C C 3 H Mn ~ 7.0k, PDI 1.08 Mn ~ 12.0k, PDI 1.08 Mn ~ 18.0k, PDI 1.08 400 nm 7 Molecular weight control of additives is important for good self assembly
Effect of Additive PDI on Self Assembly Additive: P(HA-Sty) 5wt% BCP: PS-b-PTMC, Pitch ~ 19nm Underlayer: Neutral, Sty ~ 62% Mw ~ 12.3k, PDI = 2.10 Mw ~ 12.9k, PDI = 1.08 400 nm No significant impact of SAP additive PDI on Self assembly of PS-b-PTMC 8
HA Methacrylate-based SAP Additives Bis-HAcyclohexyl MA ipr-hama HA-Sty H 3 C 3 C 3 C C 3 H 3 C C 3 H 3 C C 3 H 5 wt% additive BCP: PS-b-PTMC 400 nm 9 HA Methacrylate-based additives did not perform as well
DSA Attempt of BCP + P(HA-Sty) Additive Graphoepitaxy DSA R R PS P(HA-Sty) PTMC Neutral PS-b-PTMC + 10% P(HA-Sty) Resist BCP + SAP Secondary Ion Intensity (c/s) 1E+7 1E+6 1E+5 1E+4 1E+3 1E+2 1E+1 SIMS of BCP + SAP ilm BCP + 10% SAP on Neutral UL C Si 1E+0 0 10 20 30 40 Sputtering Time (m) Where is SAP Additive? Resist sidewalls? SAP present at substrate and air interfaces 10 Better additive design needed
Increasing Surface-activity of the Additives P(HA-Styrene) SAP Pentafluorostyrene-r-HA-Sty copolymer random 0.4 0.6 3 C C 3 H 3 C C 3 H PS-b-PTMC + 3% Additive PS-b-PTMC + 3% Additive Self-assembly defects P ~ 19 nm 400 nm 11 Lower SAP loading needed with more surface active materials
DSA of PS-b-PTMC with P(PS-r-HASty) Additive 9.5 nm HP Pitch Lamellae, 170 C / 5 min 100 nm Secondary Ion Intensity (c/s) 1E+7 1E+6 1E+5 1E+4 1E+3 1E+2 1E+1 1E+0 PS-b-PTMC + 5% P(PS-r-HASty) 100nm Si C 0 10 20 30 40 12 Sputtering Time (m) SAP mostly at BCP-air interface Good DSA with improved SAP additive
Mechanism of rientation Control with SAP Additives TBC:PTMC-PS-PTMC Triblock Copolymer, Lo:19 nm, UL:Neutral, SAP: 2 wt% w.r.t. TBC, Annealing:170 C / 5 min PHST: H-bonding only P(PS-r-AcSty): Surface active only P(PS-r-HST): Surface active & H-bonding random 80 mol% PS 80 mol% PS Parallel lamellae Mostly Parallel lamellae Perpendicular lamellae 400 nm Both hydrogen bond donors and surface active groups are needed for perpendicular orientation 13
Etch Attempt for P(TMC-S-TMC) 9.5 nm HP X-section SEM Before Etching BCP After 2 Etch 2 Etch Pitch ~ 19 nm SIS + 2 etch Trimethyl Aluminum + H2 cyclesbcp After 2 Etch 20nm Dry etching of PS-b-PTMC resulted in complete pattern collapse Moderate success with SIS + 2 etch We decided to investigate BCPs with tunable χ parameter 14
DSA Symposium Generation 2015. 10/27/15 II Polycarbonate High-χ BCPs Decreasing BCP χ by Tuning Carbonate Group Generation I BCP: PS-b-PTMC Generation II BCP: PS-b-PMeCAR Mn = 12.5k-16k, PDI = 1.03 BCP + 5% P(HA-Sty) SAP Mn = 12.5k-14.6k, PDI 1.02 BCP + 2% SAP P(HA-Sty) SAP Pitch ~ 27 nm Pitch ~ 19.5 nm 200 nm 200 nm 15 Needs special underlayer synthesis Higher χ parameter Perpendicular orientation on PS-r-PMMA ULs! Lower χ parameter Lower SAP loading needed!
PS-r-PMMA Underlayers are Neutral for Gen II BCPs! BCP: PS-b-PMeCAR, 12.5k-b-14.6k, VfPMeCAR ~ 0.48 SAP: P(HA-Sty) 2 wt% w.r.t. BCP Underlayers: PS-r-PMMA of varying composition BCP Annealing: 170 c / 5 min SMMA, S = 18% SMMA, S = 20 % SMMA, S = 22% SMMA, S = 25% SMMA, S= 30% L o ~ 19.5 nm L o ~ 19.5 nm 19.5 nm 200 nm Integration-friendly: ab compatible underlayers work for Gen II BCPs 16
Gen II BCP: PS-b-PMeCAR + P(HA-Sty) SAP Additive GISAXS for PS-b-PMeCAR + SAP DSA of PS-b-PMeCAR + SAP 100 BCP + 2 wt.% SAP Perpendicular lamellae Intensity 10 1 BCP only, no SAP Parallel lamellae 0.05 q [Å -1 ] GISAXS confirms perpendicular lamellae for 2 nd Gen BCPs + SAP 0.10 Same SAP additive works for multiple polycarbonate platforms 0.15 Graphoepitaxy of PS-b-PMeCAR+ 2 wt.% SAP on neutral underlayer What about pattern transfer of 2 nd Generation polycarbonate BCPs? 17
Dry-etching of 19.5 nm Pitch PS-b-PMeCAR 1. Spin Coat BCP + SAP, Δ 2. 2 Etch 3. C4 / CH3 Etch 4. 2/N2 Etch UL (~4 nm) SiNx (5 nm) α-carbon (20 nm) Silicon Substrate 100 nm Pattern transfer of all-organic high-χ BCP demonstrated 18
Polycarbonate BCPs for DSA Summary Top rientation Control & DSA SAP Additive 2 wt% SAP random 0.4 0.6 PS-b-PMeCAR Pattern Transfer STG2, in S Hardmask = 62 Sub-10 nm Half-pitch 3 C C 3 H Acknowledgements Guanyang Lin, Margareta Paunescu, Durairaj Baskaran, Yi Cao Merck. (PS-r-PMMA ULs and PS-H macroinitiators) Vaughn Deline IBM Almaden (SIMS) Krystelle Lionti IBM Almaden (XRR) Kevin Yager BNL (GISAXS of PS-b-PTMC) 19