Study of the fundamental contributions to line edge roughness in a 193 nm, top surface imaging system

Top surface imaging systems based on vapor phase silylation have been investigated for use at a variety of wavelengths. This approach to generating high aspect ratio, high resolution images held great promise particularly for 193 nm and EUV lithography applications. Several 193 nm top surface imaging (TSI) systems have been described that produce very high resolution (low k factor) images with wide process latitude. However, because of the line edge roughness associated with the final images, TSI systems have fallen from favor. In fact, TSI does not appear in the strategy or plan for any imaging technology at this time. Most of the 193 nm TSI systems that have been studied are based on poly(p-hydroxystyrene) resins. These polymers have an unfortunate combination of properties that limit their utility in this application. These limiting properties include (1) high optical density, (2) poor silylation contrast, and (3) low glass transition temperature of the silylated material. These shortcomings are related to inherent polymer characteristics and are responsible for the pronounced line edge roughness in the poly(p-hydroxystyrene) systems. We have synthesized certain alicyclic polymers that have higher transparency and higher glass transition temperatures. Using these polymers, we have demonstrated the ability to print high resolution features with very smooth sidewalls. This article describes the synthesis and characterization of the polymers, their application to top surface imaging at 193 nm, and the analysis that was used to tailor the processing and the polymer's physical properties to achieve optimum imaging. (C) 2000 American Vacuum Society. [S0734-211X(00)01905-3].