BCB-to-oxide bonding technology for 3D integration

Process optimization of BCB polymer to silicon oxide bonding was investigated. The suitable bonding temperature is about 300 °C, while bond failure of BCB-to-oxide bonding is observed starting from 400 °C. Bonding interface morphologies and bond strengths of BCB-to-oxide bonding were investigated as well. PECVD oxide to BCB bonding has better bonding quality than that of thermal oxide to BCB bonding. Si–O–Si bonds may be the reason of a strong BCB to oxide bonding. Water molecules link BCB and oxide surfaces during the initial contact, while Si–O–Si bonds are formed during bonding. This proposed mechanism of BCB-to-oxide bonding provides a guideline for polymer to oxide hybrid bonding technology in 3D integration.