Studies on the reaction between silane and hydrogen peroxide vapour; surface formation of planarized silica layers

Abstract

The chemistry of the reaction of gaseous silane with hydrogen peroxide vapour at low pressure, which yields commercially valuable planarized silica layers on line-etched silicon wafers, has been studied for the first time. Monitoring the mixed vapours by line-of-sight mass spectrometry and by low temperature infrared spectroscopy together with deuteriation and quantification studies indicates the reaction occurs only on surfaces, probably by a free radical mechanism. The conditions which allow the formation of self-planarizing, ‘flowy' silica films are consistent with a sol–gel process. It was found that hydroxyl radicals, formed in this work by microwave dissociation of water vapour, react in the gas phase with silane to give silica films which do not form planar layers on line-etched wafers.