APPLICATION OF PHOTOSENSITIVE POLYIMIDE

Issues in the LSI polyimide buffer coating process which uses photosensitive polyimide also as a mask of passivation film etching are reviewed. Change of lithography wave length from g-line to i-line causes the difficulty in the polyimide patterning. However, today's improved polymers, both ester type and ionic type, have enough ability to open 10um windows. Dry etching condition must be adjusted to reduce the reaction products because this process cannot apply hard asking. It is clarified that the adhesion to the molding resin after PCT is improved by F at the polyimide surface and is deteriorated by O2 plasma treatment. Fluorinated polyimide can keep good adhesion even after O2 plasma treatment. Photosensitive polyimide can reduce the process steps in the LSI buffer coating process. Latest polyimides, both ester type and ionic type, has patterning ability for the application. RIE condition and Dost-treatment which are related to the issues of reaction products and the molding resin adhesion are significant.