New positive working dry film resist

摘要

We will present a new positive working dry film resist system that is suitable for high accuracy use. The new positive working dry film resist is composed of base polymers with active hydrogen functionality, and a multifunctional vinyl ether compound plus a photo acid generator, and makes use of a chemical amplification method to allow imaging at low exposure levels of UV light. At the pre-bake stage, a ketal structure is formed by an additive reaction between the active hydrogen functional groups and the vinyl ether. Consequently, the base resin is cross-linked and the resist becomes insoluble in an alkaline developer. At the UV exposure stage, the photo acid generator forms a strong acid and the area of exposure becomes soluble in alkaline developer via an hydrolysis reaction. This new chemistry makes it possible to form a high reliability image with high contrast in comparison with conventional positive- and negative-acting systems. The new positive working dry film resist achieves on the order of 10μm Line/Space patterns plus the ability to tent 5mm diameter through holes with a resist as thin as 10μm.