Bulletin of the American Physical Society
APS March Meeting 2011
Volume 56, Number 1
Monday–Friday, March 21–25, 2011; Dallas, Texas
Session H43: Focus Session: Thin Film Block Copolymers II |
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Sponsoring Units: DPOLY Chair: Ting Xu, University of California, Berkeley Room: A306/307 |
Tuesday, March 22, 2011 8:00AM - 8:36AM |
H43.00001: Polymer Physics Prize Break |
Tuesday, March 22, 2011 8:36AM - 9:12AM |
H43.00002: Directed self-assembly of Si-containing block copolymer thin films in topographical templates Invited Speaker: Block copolymer films in which one block contains Si are attractive for nanolithographic applications due to the high etch contrast and etch resistance of the Si-rich block. We describe the microphase separation of thin films of such polymers on topographic templates made either by electron-beam writing or by etching of another block copolymer film. The self-assembled morphology is governed by the commensurability between the block copolymer and the template, and both periodic and aperiodic patterns such as meanders and junctions can be directed by appropriate template designs. Different morphologies can be formed in one block copolymer film by sequential solvent anneal steps. Results for directed assembly of diblock copolymers and triblock terpolymers are understood through 3D self consistent field theory modeling. [Preview Abstract] |
Tuesday, March 22, 2011 9:12AM - 9:24AM |
H43.00003: Thermal Manipulation of Block Copolymer Morphology by Focused Laser Spike (FLaSk) Annealing Jonathan Singer, Kevin Gotrik, Steven Kooi, Caroline Ross, Edwin Thomas Block copolymer (BCP) thin films have a high potential as a pattern transfer medium for ultra-fine ($<$10nm) features. We introduce a novel technique for performing rapid local annealing of BCP films by focused laser spike (FLaSk) heating using visible wavelengths. This process may be viewed as imposing a local instantaneous landscape in both block mobilities and interaction parameters corresponding to the temperature profile. By controlling the duration and intensity of the dose, either the rapid local perfection of the equilibrium microdomain morphology or the controlled incorporation of metastable architectures is possible. Moreover, the ultra-short FLaSk process can limit polymer degradation, allowing faster microdomain manipulation by enabling higher temperature anneals. Utilization of a direct write stage allows for deliberate control of arbitrary thermal patterns and subsequent BCP ordering, with line width near the diffraction limit. FLaSk can be applied to nearly any BCP system and performed with other ordering techniques. Direct write experiments were combined with thermal finite elements simulations to probe the various material and process parameters necessary to enhance control of spherical and cylindrical BCPs and address challenges such as the use of thicker films. [Preview Abstract] |
Tuesday, March 22, 2011 9:24AM - 9:36AM |
H43.00004: Tunable Cosolvent Annealing Affects on Block Copolymer Morphology Kevin Gotrik, Jeong Gon Son, Adam Hannon, Alfredo Alexander-Katz, Caroline Ross Being able to precisely and reproducibly control block copolymer (BCP) morphology is of interest for lithographic applications due to the techniques ability to result in feature sizes ranging from 10-100nm. We explore the morphological phase behavior that thin films (30-40nm) of poly(styrene-b-dimethylsiloxane) (PS-PDMS, 45kg/mol, $\sim $0.26 segmental Flory-Huggins interaction parameter) exhibit under different cosolvent vapors of toluene and heptane. Variation in the solvent conditions results in selective swelling of the different blocks of the copolymer depending on relative Hildebrand solubility parameters (e.g. PS- 18.5, toluene-18.3 (MPa)$^{1/2}$) resulting in cylinders, spheres, lamella, and perforatted lamella self-assembled features which can be revealed by selectively etching the PS with an oxygen plasma (50W CF4). Here we describe precision solvent vapor control while doing in situ spectral reflectometry (230-1500nm) to track swelling of the BCP films as a function of time to gain insight into this BCP system. [Preview Abstract] |
Tuesday, March 22, 2011 9:36AM - 9:48AM |
H43.00005: Annealing Techniques for Obtaining Ordered Morphologies in Poly(methacrylic acid)-Poly(methyl methacrylate) Diblock Copolymer Thin Films Yan Sun, Kevin Henderson, Zhang Jiang, Joseph Strzalka, Jin Wang, Kenneth Shull The microphase separation of block copolymers in thin films continues to be of great value for the fabrication of nanostructured materials. While highly ordered arrays of microdomains can be easily achieved in some block copolymers, proper processing of others are more challenging. Obtaining ordered morphologies in poly(methacrylic acid)-poly(methyl methacrylate) (PMAA-PMMA), a diblock possessing polyelectrolyte functionality, offers unique associative properties and aqueous reaction chemistries otherwise inaccessible by most other block copolymer films. Due to the limited choices of suitable solvents with sufficiently high vapor pressure and the thermal degradation temperature of PMAA being lower than its glass transition temperature, direct solvent and thermal annealing of PMAA-PMMA are not ideal for generating ordered nanostructures. Here, we begin by solvent annealing poly(tert-butyl methacrylate)-poly(methyl methacrylate) (PtBMA-PMMA) films at room temperature. We then thermally anneal the films to convert the PtBMA block to PMAA. We present results from atomic force microscopy (AFM) and grazing-incidence small-angle x-ray scattering (GISAXS) studies. [Preview Abstract] |
Tuesday, March 22, 2011 9:48AM - 10:00AM |
H43.00006: High-Speed Block Copolymer Self-Assembly under Ambient Conditions Dae Up Ahn, Yifu Ding Self-assembled block copolymer (BC) nanopatterns have critical application impacts on nanotemplates and scaffolds for the fabrication of nanometer scale periodic arrays, nanostructured networks and membranes for fuel cells, and high-density information storage media in computers and related devices. To achieve such application potentials, well-aligned BC nanopatterns should be reliably engineered in a thin film on a variety of functional substrates within a practical time-scale for industrial production. Here, we illustrate an exceedingly high-speed BC self-assembly under ambient conditions, which is not readily achievable in a vacuum. Only in a few seconds, BC nano-cylinders perpendicular to an energetically preferential surface have been spontaneously developed in a thin BC film under air. The time-scale for the BC self-assembly under air is at least 1000 times faster than that under vacuum. However, a micro-scale film instability that seriously impairs BC nanostructures has also rapidly evolved under air prior to the lateral self-organization of BC nano-cylinders. To suppress the evolution of micro-scale film instability and also to enhance the lateral order of BC nano-cylinders, we have imposed geometric confinements during the thermal annealing process of a thin BC film. Consequently, only in a few minutes, we have prepared hexagonally well-aligned BC nano-cylinders perpendicular to the bottom surface of geometric confinements under ambient conditions. [Preview Abstract] |
Tuesday, March 22, 2011 10:00AM - 10:12AM |
H43.00007: Directed self-assembly with density multiplication of block copolymer via controlled solvent annealing Mikihito Takenaka, Hiroshi Yoshida, Yasuhiko Tada, Teruaki Hayakawa, Yoshihito Ishida, Hirokazu Hasegawa, Go Sakaguchi, Kinichiro Yamaguchi We report density multiplication of chemically patterned template employing highly segregating polyhedral oligomeric silsesquioxane (POSS) containing block copolymer (PMMA-bPMAPOSS) for extending the technique to smaller dimensions than that attained by PS-b-PMMA. PMMA-b-PMAPOSS which self-assembles into hexagonally closed packed (hcp) array of dots with lattice spacing d=13nm was spin coated on the chemical template with doubled hcp lattice spacing d=26nm, and annealed under controlled CS$_{2}$ atmosphere. By tuning the swell ratio of PMMA-b-PMAPOSS, ordered array of dots with d=13nm, which correspond to 3.5Tbit/in$^{2}$ was obtained by multiplying pattern density of the chemical template in a factor of 4. This work was supported by New Energy and Industrial Technology Development Organization, Japan. [Preview Abstract] |
Tuesday, March 22, 2011 10:12AM - 10:24AM |
H43.00008: Temperature Gradient effects in Directed Assembly of Block Copolymer Films via Cold Zone Annealing Gurpreet Singh, Manish Kulkarni, Kevin Yager, Brian Berry, Alamgir Karim Vertically oriented micro-phases of block copolymers (BCPs) are generally preferable for applications like organic photovoltaic devices and nanoscale lithography. Here we demonstrate a Cold Zone Annealing (CZA) technique that produces a very sharp thermal gradient in contrast to our previous studies that produced well-ordered parallel BCP microphases [1]. Under these conditions, initial experiments on cold zone annealed PS-b-PMMA BCP films, yielded long range vertical orientation order in PMMA cylinders. GISAXS analysis indicates that the vertical morphology is maintained throughout the film thickness. Comparison of the CZA with conventional oven annealed samples show a magnitude of improvement in the ordering of BCP phases. \\[4pt] [1] Berry et al., \textit{Nano Lett}., \textbf{7}, pg 2789 (2007) [Preview Abstract] |
Tuesday, March 22, 2011 10:24AM - 10:36AM |
H43.00009: The dynamics of lamellar re-orientation in free-standing diblock copolymer films: flipping the morphology from edge-on to flat-on Robert D. Peters, Kari Dalnoki-Veress Many exquisite structures formed by diblock copolymers have been studied rigorously over the past two decades. Using a symmetric polystyrene-poly(methyl methacrylate) diblock copolymer, we prepare thin films on a substrate which form lamellae oriented perpendicular to the film interfaces. These ``edge-on'' samples are subsequently transferred, by floating onto water, to produce free-standing films with a symmetric boundary condition. Upon annealing these free-standing films, the lamellae switch from edge-on, to ``flat-on'' such that the domains are oriented parallel to the interface. Using atomic force microscopy, we study the dynamics of pattern formation as lamellae flip from the edge-on to flat-on morphology. [Preview Abstract] |
Tuesday, March 22, 2011 10:36AM - 10:48AM |
H43.00010: New approaches to directing self-assembly and alignment of block copolymer Hanqiong Hu, Pawel Majewski, Chinedum Osuji Directed self-assembly of block copolymers (BCPs) has been explored extensively using a variety of methods to simultaneously develop long-range order and exert orientational control over microphase separated structures. Here we propose two new routes for directing self-assembly in BCPs. First we discuss solvent vapor permeation which is based on pressure driven transport of a solvent vapor through a free-standing film. We demonstrate that alignment of BCP interfaces parallel to the vapor flux may be achieved rapidly in mm-scale thick films of high molecular weight BCP. Secondly, we present the use of electrospray for controlled deposition of block copolymer thin films. We speculate that morphology can be dictated by thermal equilibration in the presence of a pre-existing pattern or substrate template and that the ultra-slow growth afforded by electrospray permits persistence of this pattern beyond the 1 micron scale where conventional surface directed morphologies degenerate. [Preview Abstract] |
Tuesday, March 22, 2011 10:48AM - 11:00AM |
H43.00011: A novel approach to achieve perpendicular long range order alignment in lamella PS-b-PEO system Parvaneh Mokarian- Tabari, Timothy W. Collins, Justin D. Holmes, Michael A. Morris Here, we introduce a novel approach for obtaining perpendicular alignment in lamella forming PS-b-PEO system. The vertical alignment of layers in diblock copolymer thin films has great potential for producing nanowires used in nanofabrication of electronic devices. However, due to selective surface interaction of the polymers with the substrate, perpendicular alignment usually requires neutralisation of the surface by means of brushes or making pre-pattern substrates which could be complicated and time consuming. Applying our novel approach named ``combinatorial annealing'' which consists of two stages of thermal and solvent annealing process, we have successfully created parallel lines (without a brush). After selective etching of one block, the remaining template is pattern transferred to a silicon substrate leading to manufacturing of sub 20 nm silicon nanowires. [Preview Abstract] |
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