Negative-Tone Photo-Definable Polyimide with High Thermal Stability and Thick Film Processability

High voltage power semiconductor requires higher polyimide insulation properties. We have designed a polyimide with high thermal stability, high light transparency and alkali dissolvable polyimide that is capable of passivating thick layer of polyimide with large topographys. A novel negative-tone photo-definable polyimide was formulated with cross linking reagent that can easily decompose during cure and a photo-initiator that initiates well during lithography. Our novel Negative photo sensitive polyimide, PSPI-1, has a patternable capability up 16 mm thickness on silicon with 350mJ/cm ² . PSPI-1 showed higher patternability than of the conventional polyimide. The cured film showed excellent properties as follows: 310 °c glass transition temperature (Tg), 500 °C weight loss temperature, 40% elongation, no short observation during bias-HAST (130 °C. 96%, 100hr, 100V/30mm line&space) and good adhesion Si to Cu and substrates. These results indicated a possibility for this novel PSPI-1 to be applicable for passivating power semiconductor.