Integration and electrical characterization of photosensitive polyimide

A base line process of photosensitive polyimide was developed to significantly reduce cycle time in backend polyimide processes as compared to the use of conventional nonphotosensitive polyimide. A 6 μm resolution was obtained by the use of a wet etch process of photosensitive polyimide (PSPI) in aqueous tetramethylammonium hydroxide developer. The feasibility of the polyimide as a passivation stress-buffer layer and passivation-etch mask was also demonstrated. Electrical characterization was performed to measure the surface resistance and the intralevel leakage current along the interface between the polyimide and tetraethylorthosilicate. These findings suggested that reduction of the moisture content of the polymer films is critical to ensure electrical isolation during the integration of PSPI into multilevel structures.