A Novel Polymer Material for Low- Temperature Hybrid Bonding and Flexible Substrate Applications

As transistor density increases, 3D integrated circuits and advanced packaging technologies are crucial for extending Moore's Law. Traditional polymer material challenges include such as warpage in organic interposers with multiple redistribution layers (RDLs) and reliability issues due to mismatches in the coefficient of thermal expansion (CTE). To address these issues, a novel polymer material has been developed. This material not only has a low CTE but also exhibits a higher Young's modulus compared to other polymers, making it highly promising for flexible substrate applications. The polymer was used for room-temperature bonding, combining ultra-thin glass (UTG) with polyimide (PI), and then was subjected to a 200,000-cycle bending test. The results demonstrated excellent flexibility and stability of the composite polymer structure on flexible substrates. In addition, the polymer was applied in low-temperature copper/polymer hybrid bonding, achieving reliable bonding at 160°C, and its electrical performance and high reliability were confirmed through thermal cycling tests (TCT). These findings underscore the potential of this polymer in flexible substrate and hybrid bonding applications, providing a practical and effective solution for achieving superior bonding and electrical performance at reduced temperatures.