Surface Morphology Diagram for Cylinder-Forming Block Copolymer Thin Films Xiaohua Zhang Center for Soft Condensed Matter Physics and Interdisciplinary Research Soochow University

Phase diagram for a block copolymer with various structures Current Solutions Needs - 3D nanostructure Manufacturing - 3D characterization of nanostructure - Control of 3D nanostructure Current Problems - 2D structures - Physical Template 200 nm Y. Gong et al Macromolecules , 3369 T. Russell et al Adv. Mater , 226 Background AB Orientation of Cylinders T. Russell et al Langmuir, 2008, 24, 3545

Challenges Contain defects in many self assembled nanostructures. Lack sufficient long-range order for certain nanotechnology applications. O 2 RIE CF4 RIE J. Cheng, Nature Materials, 3, (2004) O 2 RIE CF4 RIE 35 nm period Hitachi Global Storage Technologies Self-assembling Materials for Bottom-up Nanofabrication Processes

Assembly of Block Copolymer Films Our goal: Develop critical measurement solutions that enable nanomanufacturing with guided block copolymer assembly for next generation magnetic data storage, nanoscale electronics, and high efficiency membranes for energy. Method: Combine unique modeling platforms with precision thermal processing techniques to enable the development of small angle x-ray and neutron scattering to measure structural uniformity, including orientation distributions, and pattern placement in self-assembled polymer films within templated surfaces. Controlling Orientation using Cold Zone Annealing (CZA), sample preparation procedure and unique thermal processing technique Metrology of Orientation in Nanostructured Films 3D Nanostructure for Cylinder-Forming Block Copolymer Thin Films

Spin Coating Flow Coating without Residual Solvent 3D Nanostructure Flow Coating 200nm C. M Stafford et al. Rev. Sci. Instr. 11(2006) Materials: Poly (styrene-block-methyl methacrylate) Mn: PS(35500)-PMMA(12200) Mw/Mn: 1.04 Surface Morphology Diagram of PS-PMMA Block Copolymer Films on Oxide Silicon Substrate

200nm Film thickness:  120 nm Annealing: 155˚C for 15 h Prebaking: 93 ˚C for 15 h Spin-coated in airFlow-coated in air Spin-coated in toluene vapor Spin-coated in toluene vapor & prebaked prior to annealing Sample Preparation Procedure Dependence

Surface Morphology Diagram

AFM phase images of flow coated PS-b-PMMA block copolymers after annealing at 147 ˚C for 15 h. ss PMMA PS Increasing Film Thickness 58nm71nm 104nm 130nm 168nm 86nm 200nm

θθ Incident neutrons Detector Sample θ θ qxqx qzqz 2θ2θ 3D Characterization of Nanostructure by Neutron Reflectivity (NR) NCNR in NIST

dPS-b-PMMA, 80 nm, 147 o C for 15 h 200nm Air Si

We convert from beam-coordinates (q x,q y,q z ) to sample-coordinates (Q x,Q y,Q z ) using a rotation matrix Orientation Distribution Measurement of 3D Nanostructure by RSANS QyQy QxQx QzQz

Samples show a mix of parallel and perpendicular cylinder scattering Hexagonal pattern from laying-down cylinders Scattering peak from standing-up cylinders Low-q scattering from size disorder Weak ring from random component

Annealing:147ºC for 15h Content of perpendicular cylinders:80% Film thickness:136nm 200nm Annealing:165ºC for 15h Content of perpendicular cylinders:59% Film thickness:141nm Data was fit by extending the model of Ruland and Smarsly. Ruland, W.; Smarsly, B. J. Appl. Cryst. 2005, 38,

16% Residual Solvent 12% Residual Solvent PS-b-PMMA in deuterated toluene NR Measurements on Residual Solvent in PS-b-PMMA Films Self-assembly Driving Force of 3D Nanostructure

PS Film Thickness and Molecular Weight Dependence

NR data (symbols) of as-cast, one-step (93 o C for 15 h) and two-step (93 o C for 15 h followed by 155 o C for another 15 h) annealed PMMA films with as-cast film thickness of 121 nm at fixed molecular weight (20 kg/mol). NR scans (symbols) measured from the PMMA films of different thickness at fixed molecular weight (20 kg/mol). PMMA Films

FTIR Characterization of Residual Solvent in BCP Films SamplesResidual solvent concentration (weight) PMMA as cast film from 3% d-Toluene solution1.2 ± 0.2 % PMMA baked and dried in vacuum oven (repeat)< 0.2% PS as cast from 3% d-Toluene solution (repeat)< 0.4% PS baked and dried in vacuum oven< 0.4% The estimation of residual d-toluene concentration is based on its characteristic peak located around 2274 cm -1. Calibration is made with the area ratio of the strong bands corresponding to d-toluene (2274 cm -1 ) and PMMA (1730 cm -1 ) in the FTIR spectra of 3% polymer solution. PS (51kg/mol) PMMA (20kg/mol) Film thickness : 160 nm. Macromolecules 2010, 43, 1117–1123. ACS Nano, 2008, 2,

Film preparation procedure, and other processing effects, cannot be ignored in nanomanufacturing applications. interplay between intrinsic BCP structure and processing conditionsFundamentally demonstrate the interplay between intrinsic BCP structure and processing conditions. orientational distributionR-SANS and NR can deduce orientational distribution in BCP cylinder thin films. Summary