Positive working photosensitive polymers for semiconductor surface coating

A positive working photosensitive polymer for semiconductor surface coating has been developed. Two types of thermal stable polymers, polyimide with hydroxyl groups and polybenzoxazole (PBO) precursor, were examined. It was confirmed that PBO precursor is superior to polyimide with hydroxyl groups with respect to solvent and humidity resistance. But PBO precursor had only poor adhesion to silicon wafers, and their patterns were stripped easily from substrates in developing with alkaline solution. The effect of the addition of silane coupling agents and the modification of PBO precursor with silicone compound in order to improve their adhesion properties is discussed. As a result, it was found that they had excellent adhesion to silicon wafer during development when they are modified with some silicone polyimides. Through these results, a positive working photosensitive polymer with practical sensitivity and resolution was developed