Preparation of Hot Water-Resistant Silica Thin Films from Polysilazane Solution at Room Temperature

摘要

Perhydropolysilazane (PHPS) films were deposited on single-crystal Si substrates by spin-coating using a xylene solution of PHPS,and then suspended over 1 mol L~(-1) ammonia water at room temperature.The PHPS-to-silica conversion occurring on the exposure to the ammonia water vapor was studied by infrared absorption spectroscopy.Si-H and N-H infrared absorption peaks decreased and Si-O-Si bands increased,showing PHPS-to-silica conversion;the conversion was almost completed in 6 h.The exposed films were soaked in 80degC water for 24 h,and the reduction in thickness on soaking was evaluated.The PHPS-derived films suspended over the ammonia water for 6 h exhibited only 2% reduction in thickness on soaking in 80degC water.Alkoxide-derived silica gel films dried in the ambient atmosphere or suspended over the ammonia water,on the other hand,exhibited significant reduction in thickness on soaking in 80degC water.