A Novel Surface Humidity Controlled Bonder for Low-Temperature Wafer Bonding

Hydrophilic bonding is commonly used in the wafer bonding field. Water management is of great importance to obtain good bonding quality over the entire bonded pairs. However, current wafer bonding equipments do not have the function of regulating the surface humidity prior to bonding. It is difficult to make a quantitative study on the role of moistures in the bonding process. In this paper, a novel surface humidity controlled bonder is developed to optimize the water adsorption on the wafer surface prior to bonding and improve the bonding quality using cooling as well as heating functions. For the sufficient surface humidity, the water molecules may bond together via Si-OH groups on the silica surfaces, and then they can compensate the gap between the bonded wafers resulting a weak hydrogen-bonding connected Si-OH center dot center dot center dot(H2O)(x) center dot center dot center dot HO-Si interface structure forming a good prebonding interface.