Low Temperature Wafer Bonding

Abstract

Low temperature wafer bonding is requested in many applications. Most of them involve silicon or silicon dioxide bonding interfaces. Studying bonding process / mechanism in the low temperature range (<400oC) is therefore very important. But depending on the oxide thickness involved, bonding behaviors are different. In this paper, a quick overview presents the state of the art in silicon oxide or silicon bonding progress mainly focused on the bonding energy and defectivity with only low thermal treatment used after bonding. Specifically for thin oxide layer or silicon direct bonding, the defectivity evolution remains the most important issue. Different bonding mechanisms are proposed in order to understand this behavior. Such an understanding allows us to propose different processes which can minimize or even suppress the bonding defects.