Characterizing the three-dimensional structure of block copolymers via sequential infiltration synthesis and scanning transmission electron tomography

Published

May 26, 2015

Author(s)

Tamar Segal-Peretz, Jonathan P. Winterstein, Manolis Doxastakis, Abelardo Ramirez-Hernandez, Mahua Biswas, Jiaxing Ren, Hyo S. Suh, Seth B. Darling, James Alexander Liddle, Jeffrey Elam, Juan J. de Pablo, Nestor Zaluzec, Paul Nealey

Abstract

Understanding and controlling the three-dimensional structure of block copolymer (BCP) thin films is critical for utilizing these materials for sub-20 nm nanopatterning in semiconductor devices, as well as in membranes and solar cell applications. Combining an atomic layer deposition (ALD) based technique for enhancing the contrast of BCPs in transmission electron microscopy (TEM) together with scanning TEM (STEM) tomography reveals and characterizes the three-dimensional structures of poly(styrene-block-methyl methacrylate) (PS-b-PMMA) thin films with great clarity. Sequential infiltration synthesis (SIS), a block-selective technique for growing inorganic materials in BCPs films in ALD, and an emerging tool for enhancing the etch contrast of BCPs, was harnessed to significantly enhance the high-angle scattering from the polar domains of BCP films in the TEM. The power of combining SIS and STEM tomography for three dimensional (3D) characterization of BCPs films was demonstrated with the following cases: self-assembled cylindrical, lamellar, and spherical PS-PMMA thin films. In all cases, STEM tomography has revealed 3D structures that were hidden underneath the surface, including: 1) the 3D structure of defects in cylindrical and lamellar phases, 2) non-perpendicular 3D surface of grain boundaries in the cylindrical phase, and 3) the 3D arrangement of spheres in body centered cubic (BCC) and hexagonal closed pack (HCP) morphologies in the spherical phase. The 3D data of the spherical morphologies was compared to coarse-grained simulations and assisted in validating the simulations' parameters. STEM tomography of SIS-treated BCP films enables the characterization of the exact structure used for pattern transfer, and can lead to better understating of the physics which is utilized in BCP lithography.

Citation

ACS Nano

Volume

9

Issue

5

Pub Type

Journals

Download Paper

https://doi.org/10.1021/acsnano.5b01013

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Citation

Segal-Peretz, T. , Winterstein, J. , Doxastakis, M. , Ramirez-Hernandez, A. , Biswas, M. , Ren, J. , Suh, H. , Darling, S. , Liddle, J. , Elam, J. , de Pablo, J. , Zaluzec, N. and Nealey, P. (2015), Characterizing the three-dimensional structure of block copolymers via sequential infiltration synthesis and scanning transmission electron tomography, ACS Nano, [online], https://doi.org/10.1021/acsnano.5b01013, https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=917920 (Accessed April 9, 2025)