ABSTRACT
With the progress of electronic devices toward higher integration, wiring density, signal processing, and reliability, new heat stable dielectrics are required for interlayer dielectrics and protective coatings in the devices, instead of common inorganic dielectrics. Polyimide, which is one of the most heat stable polymers, is a good candidate for the applications. Dielectric pattern engraving is indispensable for the applications. Three methods of polyimide pattern formation have been applied: with a negative working photoresist as an etching mask, the polyimide is etched with hydrazine; with a positive working photoresist as an etching mask, the polyimide precursor is etched with an aqueous alkaline developer for the photoresist, simultaneously with the developing of the photoresist; and by use of a polyimide precursor endowed with photosensitivity, the polyimide precursor is subjected to pattern formation. This chapter describes the method of synthesis to give photosensitivity to a polyimide precursor, the mechanism of photosensitivity, and the influence of the photosensitizing technique on film properties.
