Effect of Prebonding Surface Treatments on Si-Si Direct Bonding : Bonding Void Decrease

Comparisons of various plasma assisted low temperature wafer bonding procedures have been conducted in order to carry out reliable void-free and high bonding strength. In this way, reactive ion etching (RIE), microwaves (MW) and inductive coupled plasma (ICP) modes have been investigated as surface cleaning and activation processes before Si-Si direct bonding. Moreover impacts of some additional prebonding surface treatments have been analyzed for such bonded structures. Using these additional treatments, focus has been specifically made on efficiencies to perform void-free and high bonding strength for Si-Si direct bonding thanks to prebonding 300{degree sign} heating and/or on under-vacuum bonding.