Base-catalyzed photosensitive polyimide

Abstract

The application of polyimide in electronic devices is made considerably easier when the polyimide precuresor can be directly imaged to allow for fabrication of metal lines and vias. Direct polyimide imaging (photosensitive polyimide or (PSPI) minimizes the number of processing steps thus increasing throughput. This paper describes the development of a new approach to PSPI which is based chemically on the propensity for polyamic esters to imidize rapidly in the presence of catalytic quantities of amines. By incorporating amine photogenerators along with polyamic esters, it has been possible to develop schemes for imaging polyamic esters. Polymer films containing polyamic ester and amine photogenerator are irradiated to produce an amine, which is used to catalyze the partial imidization of polymer in the exposed portion of the film. The unexposed film containing only polyamic ester and amine photogenerator is more soluble than the partially imidized film in developer solvents and can be selectively removed. Subsequent to development, the negatively imaged polymer film is cured to polyimide at high temperature.