Temporary Bonding and De-Bonding for Multichip-to-Wafer 3D Integration Process Using Spin-on Glass and Hydrogenated Amorphous Si

Temporary bonding and de-bonding techniques using respectively spin-on glass (SOG) and hydrogenated amorphous-Si (a-Si:H) have been examined for multichip-to-wafer three-dimensional (3D) integration process. In this study, a 280 um-thick known good dies of 5 mm × 5 mm in size were temporarily bonded to a pre-deposited (a-Si:H (100 nm) and SOG (400 nm)) support glass wafer. After completing the die thinning and TSV formation processes, the dies were de-bonded using 248 nm excimer laser. The surfaces of de-bonded chip/wafer and glass substrate were meticulously investigated using x-ray photoelectron spectroscopy (XPS). From C1s, O1s, and Si1s XPS data, it is inferred that the de-bonding occurs in the a-Si:H layer. It reveals that the interface between the SOG and a-Si:H layer was highly intact, and the bonding strength is good enough to withstand the harsh environment during die/wafer thinning and TSV formation processes.