Effect of wafer-scale shape variations and mounting in wafer bonding

The wafer-scale shape of a bonded wafer pair is determined by the initial shapes of the wafers and the mounting configuration used during bonding. In this work, a combination of modeling and experiments that demonstrate the effect of the initial shapes of the wafers and mounting on the shape of the bonded pair are presented. Analytical and fmite element mechanics models that allow the final shape and residual stress of the bonded pair to be predicted for wafers bonded in different mounting configurations are presented. Experiments, in which wafers were bonded and the shapes of the initial wafers and bonded pair were measured, are reported. The measured shape of the bonded pair is compared to predictions made using the model in order to validate the approach proposed. The models enable intelligent design of bonding tools and can be coupled with appropriate metrology for improved process control.