Anodic bonding of silicon to silicon wafers coated with aluminium, silicon oxide, polysilicon or silicon nitride

Abstract

Silicon to silicon wafer bonding by use of sputter deposited borosilicate film is a promising mounting method for micromechanical components. This method has been developed to bond 3 inch borosilicate sputter coated silicon wafers to silicon wafers coated either with aluminium, silicon dioxide, polysilicon or silicon nitride. The bondings were performed at temperatures ranging from 300 to 400 °C which enables application of this technique on metallised devices. The bond strengths of the different samples bonded with these methods are all in the region 5–25 MPa. Some samples were exposed to water for 300 h to test the media compatibility, and some samples were thermal shock tested by repeatedly exposing to liquid nitrogen. No significant difference in bond strength has yet been verified statistically for the different sample configurations. We have also observed good correlation between destructive bond strength testing and non-destructive infrared microscope inspection.