Characterizing the Three-Dimensional Structure of Block Copolymers via Sequential Infiltration Synthesis and Scanning Transmission Electron Tomography

Journal Article · Tue May 12 00:00:00 EDT 2015 · ACS Nano

DOI:https://doi.org/10.1021/acsnano.5b01013· OSTI ID:1392502

Segal-Peretz, Tamar ^[1]; Winterstein, Jonathan ^[2]; Doxastakis, Manolis ^[1]; Ramírez-Hernández, Abelardo ^[1]; Biswas, Mahua; Ren, Jiaxing ^[1]; Suh, Hyo Seon ^[1]; Darling, Seth B. ^[1]; Liddle, J. Alexander ^[2]; Elam, Jeffrey W.; de Pablo, Juan J. ^[1]; Zaluzec, Nestor J.; Nealey, Paul F. ^[1]

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1. Institute for Molecular Engineering, University of Chicago, 5747 South Ellis Avenue, Chicago, Illinois 60637, United States
2. Center for Nanoscale Science and Technology, National Institute of Standards and Technology, 100 Bureau Drive, Gaithersburg, Maryland 20899, United States

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.

• Research Organization: Argonne National Lab. (ANL), Argonne, IL (United States)
• Sponsoring Organization: USDOE Office of Science (SC), Basic Energy Sciences (BES)
• DOE Contract Number: AC02-06CH11357
• OSTI ID: 1392502
• Journal Information: ACS Nano, Vol. 9, Issue 5; ISSN 1936-0851
• Publisher: American Chemical Society (ACS)
• Country of Publication: United States
• Language: English

Related Subjects

Block copolymers
SIS
STEM
TEM
self - assembly
tomography