Warpage Modeling and Characterization to Simulate the Fabrication Process of Wafer-Level Adhesive Bonding

Since the array of wafer-level packages formed by bonding of a cap wafer to a substrate wafer, how to well encapsulate the intricate sensor devices in wafer-level is the critical issue in the development of image sensor products. This paper presents an analytical model for design and fabrication of wafer-level adhesive bonding. A novel mechanical approach is proposed, which considers each layer in bonded wafer as a beam-type plate with effective material properties. Based on this mathematical modeling, the wafer warpage under thermal loading is predicted and compared to the experimental measurements. It is shown that our newly developed wafer warpage modeling offers simple and precise evaluation of wafer-level adhesive bonding process.