All Dry Lithography Processes and Mechanistic Studies with Poly(methacrylonitrile) and Related Polymers

Poly(methacrylonitrile) and related polymers have been found to be uniquely suited for all dry lithographic processes. The polymer patterns are generated by thermal treatment followed by oxygen plasma removal. Poly-(methacrylonitrile) and copolymer (acrylonitrile-methacrylic acid) yield patterns with positive tone, while poly(a-chloroacrylonitrile) provides negative tone patterns. Oxygen plasma etch rate differs for the exposed and the unexposed parts. The polymer patterns, after heat-treatment, become highly CF4 plasma etch resistant, providing well-defined SiOVSi patterns. Thus, with 2/μm thick films of poly(methacrylonitrile) exposed to electron dose of 5 X 10-6 C/cm2, 1.5-1.8 μm deep SiO2Si patterns are generated with high resolution by all dry processes; the resist patterns of 1.5 μm width, depth, and spacing are obtained at 5 x 10-6 C/cm2 with the wall angle of 65°. Mechanistic studies including EPR, ESCA, and mass spectroscopic measurements were carried out to provide a mechanism. © 1981, The Electrochemical Society, Inc. All rights reserved.