A Novel Multifunctional Single-Layer Adhesive Used for both Temporary Bonding and Mechanical Debonding in Wafer-Level Packaging Applications

Temporary bonding (TB) and debonding (DB) of wafers have been widely developed and applied over the last decade in various wafer-level packaging technologies, such as package-on-package (PoP), fan-out integration, and 2.5D and 3D integration using through-silicon vias (TSVs). The materials used to achieve TB and DB are extremely critical and the industry's current best practice is the use of two layers of materials (bonding layer and release layer). In this paper, a novel single-layer adhesive is presented to possess both functions of TB with mechanical DB. The properties of this material empower the capabilities of handling ultrathin wafers, supporting very low warpage for high-stress substrates, and surviving high-temperature processing. Testing on a blank silicon wafer thinned down to 20 µm showed neither defects nor edge chipping. In addition, a thermal simulation of 250°C for 30 minutes also passed qualification. Less than 30 µm warpage on an 8” wafer was also observed, which proves the material is friendly to high-stress substrates. More importantly, using fewer layers means fewer total processes, fewer cleaning steps, and lower cost of ownership.