Dissolution Study of a Novolak-Based Photoresist Based on a Developer Diffusion Model

Abstract

Dissolution characteristics of a positive chemically amplified photoresist, AZ-PF514 from Hoechst Celanese, have been studied. Development rate monitor data for different developer concentrations are analyzed. The experimental dissolution rates of the X-ray-exposed photoresist are examined in view of the dissolution model proposed earlier by Reiser. Parameters of Reiser's model associated with the diffusion of an aqueous base through a thin penetration layer and solubility of a phenolate complex in an aqueous base solution are derived for different X-ray exposure conditions. Reiser's dissolution model was used to simulate the developed photoresist pattern profile. An example of 0.25 µm pattern development simulation using a dose-dependent coefficient for diffusion of a developer base into polymer is demonstrated.