Silicon Nitride Surface Conversion into Oxide to Enable Hydrophilic Bonding

Abstract

Oxygen plasma was used to convert the top part of Si3N4 film into SiO2. Surface roughness remarkably improves because of the process. SiO2, at surface now allows rendering surface hydrophilic. Both effects - smoothening and conversion - are favorable for further wafer bonding. Silicon wafers with the top-reoxidized nitride film successfully bond to glass substrates. The bonding allowed layer transfer. Silicon-on-glass substrates with a barrier nitride film between the silicon and glass were fabricated.