Thin bilayer resists approach for 193nm and future photolithography

摘要

Resist aspect ratio has always been an issue for lithographic processes. Smaller CD forces the use of thinner resist films, but dry etch needs a certain amount of thickness in the resist. Various techniques have been proposed and researched to overcome these single-layer resist limitations. Bilayer Si-containing resists are a technique of interest and a strong candidate to replace CVD processes. In this paper, we have characterized bilayer resists and their dry-develop processes, and sought possible uses for advanced lithography, especially by using a thin film (70 nm-90nm). Bilayer resist dry-develop consists of a film shrink as in an exposure reaction with an early-stage resist surface oxidation. We discuss material requirements for this purpose and provide some after-dry-develop images with small CD.