Field-assisted bonding of glass to Si-Au eutectic solder for packaging applications

A new approach for high-yield bonding of Pyrex 7740 glass to a silicon wafer using field-assisted glass to Si-Au eutectic bonding is presented. It is found that by applying an anodic bias, as is typically used in direct Si-glass wafer bonding, in a standard Si-Au eutectic bond, one can obtain a significant improvement in bond quality, uniformity, and reproducibility. Experimental results obtained from bonded silicon wafers and Pyrex 7740 glass wafers using silicon-gold eutectic solder on planar and non-planar surfaces are presented. Samples bonded at 410°C show bond strengths of >5.24MPa which falls within the range 2 to 25MPa reported for direct Si-Pyrex anodic bonding. Other samples bonded at 450°C show a bond strength >31.4MPa.