Low cost, room temperature debondable spin-on temporary bonding solution: A key enabler for 2.5D/3D IC packaging

We report the development of a bi-layer spin on temporary bonding solution (TBS) which eliminates the need for specialized equipment for wafer pretreatment to enable bonding or wafer post treatment for debonding. Thus it greatly increases the throughput of the temporary bonding/debonding process. It also provides a total thickness variation (TTV) of less than 1 μm for spin coated films on both 200 mm and 300 mm wafers which enable the TTV of 300 mm bonded pairs to be 2-3 μm for bumped wafers using 70 and 100 μm thick adhesive films after backgrinding for an unoptimized bonding process. Furthermore, we have demonstrated the chemical and thermal stability of both the material and the bonded pair by exposing the bonded wafer pair to common chemicals (phosphoric acid, nitric acid, organic solvents etc.) and temperature conditions (up to 300 C) used in the TSV process. Additionally, the time taken for the entire spin coat-bond-debond process was less than 15 minutes with room for further improvement. Based on the current results, it is expected that the current bi-layer based temporary bonding solution has the potential to play an important role in enabling the high volume manufacturing of 2.5D/3D IC stacking.