A novel temporary adhesive for thin wafer handling

Abstract

3D integrated circuits (3DICs) by stacking electronic devices can increase system functionality while decreasing the overall footprint. Through silicon via (TSV) technology based on thin wafers (typically below 100 m) has been developed to realize 3DIC stacking over the last decades. Due to their fragileness and tendency of warping, thin device wafer need to be bonded firmly to a carrier wafer during TSV processing and readily separated from the carrier after processing. Adhesives with high temperature tolerance and ease of debonding are critical for the bonding/debonding process. In this present study, a temporary adhesive based on a thermoplastic, which can be debonded by a thermal-sliding method, has been developed. Formulas were optimized to achieve void-free adhesive layer, high throughput (i.e. short bonding and debonding times) and high reliability in the bonded system. The properties of the as-prepared adhesive including the viscosity at different temperatures, thermal and chemical stabilities, thickness and homogeneity of the adhesive layer, adhesion strength and the process of clean-up were investigated systematically.The novel adhesive showed excellent thermal stability and chemical resistance and convenient post-processing, and is easy to process for high-volume manufacturing. These findings extend the candidate polymers for temporary bonding materials and can ultimately promote the practical application of TSV technology.