Relationship between resist performance and diffusion in chemically amplified resist systems

摘要

This paper describes a method to measure acid diffusion in different negative I-line resist systems. Diffusion of this acid plays a critical part in the image formation process. While some diffusion is necessary to achieve high resist sensitivity, excessive acid diffusion can cause an unacceptable loss of resolution. For this reason, diffusion must be controlled within certain limits during standard resist processing. The threshold crosslink theory of image formation, which states that a minimum concentration of acid is required to render the resist insoluble for a given development condition can be used in conjunction with a reaction-diffusion model to determine the magnitude of acid diffusion in the resist. This relatively straightforward method of measuring acid diffusion is then applied to determining an optimum resist process. Several different negative I-line acid catalyzed resists are investigated and the differences in the magnitude of acid diffusion are determined.