Thermally Reversible and Crosslinked Polyurethane Based on Diels-Alder Chemistry for Ultrathin Wafer Temporary Bonding at Low-Temperature

2.5D and 3D Integration technology using temporary bonding has become main stream in the semiconductor industry in recent years. However, thermal stability, low damage, and debonding at comparative low temperature are still areas of challenge. In this present study, a novel three-dimensional crosslinked polyurethane (3DPU) based on thermal reversible Diels-Alder chemistry, which can be used as temporary bonding adhesive to support wafer thinning and back side processes and be de-bonded by typical thermal-sliding method at comparatively low-temperature, has been developed. The crosslinked 3DPU showed high thermal stability and excellent adhesion strength both at room temperature and higher temperature. The adhesion strength of 3DPU decreased when the wafer pair was heat to the de-bonding temperature (150 oC) when the retro-DA reaction happened which guaranteed a low-temperature de-bonding process.