High‐Temperature‐Post‐Exposure Bake Process (HIT‐PEB) for Base‐Developable Polyimides Consisting of Diazonaphthoquinones and Polyamic Acids

Abstract

A process, which makes it possible for polyimide resists to be developed using dilute base aqueous solutions, is reported. The process contains soft bake, UV exposure, post exposure bake and development with basic aqueous solutions. The post exposure bake at a temperature range from 140 to 160°C, which is higher than usual, is the feature of this process. The polyimide resists consist of polyamic acids and diazonaphthoquinone 4‐sulfonic acid esters, whose compositions are not novel and have appeared in several patents and papers. However, the resists consisting of polyamic acids and diazo compounds usually had only low dissolution selectivity between exposed areas and unexposed areas. It was therefore difficult to obtain fine patterns. The high temperature post exposure bake (HIT‐PEB) made it possible to obtain five patterns and three micron negative patterns were fabricated. This process is the simplest way to realize polyimide resists developable with basic aqueous solutions.