Thermally and mechanically reliable photoresist for redistribution layer for advanced packaging

A photoresist with high mechanical and thermal reliability is required for redistribution layer (RDL) formation to improve integration density and realize thinner packaging for semiconductor industries. We report on a photoresist made from a mixture of a carboxyl group containing polyimide–phenol polymer and a slide-ring polymer. The photoresist showed high toughness, low coefficient of thermal expansion, and excellent long-term thermal stability, keeping its lithography properties, such as 8-μm-diameter via-hole having the depth of 15 μm, and 200°C to 220°C low-temperature curability. This resist will help panel-level-package technology by improving its reliability, and also integrate RDL for automotive packaging.