Development of Polyimide Base Photosensitive Permanent Bonding Adhesive for Middle to Low Temperature Hybrid Bonding Processes

A new polyimide-based photosensitive bonding adhesive ("New PI") was developed for 3D hybrid bonding at low temperatures by redesigning key components of the formulation. The New PI was cured at 230°C and bonded at 250°C or less using a conventional flip-chip bonder, showing great potential as a permanent hybrid bonding dielectric material. Furthermore, the advantages of polyimide (PI) in the hybrid bonding process were investigated and it was found to have higher step-absorbing properties compared to inorganic material. It is considered that these properties contribute to a high bonding yield of PI.