Adhesion Property of Polyimide and Passivation Layer for Polymer/metal Wafer-Level Hybrid Bonding in 3D Integration

In this paper, the four-point bending method experiments were carried out with different polyimides and passivation layers for realization of adhesion property below 400°C. Three types of passivation layers, thermal oxide, tetraethoxysilane (TEOS) oxide, silicon nitride, and three types of polyimides, with hydrophobic silane, with hydrophilic silane and without silane, and annealing temperature were all considered in this paper. Moreover, the relation between adhesion strength and surface roughness is discussed. Finally, a low thermal budget (250-375°C) polyimide/metal hybrid bonding scheme with good stress release was proposed for future hybrid bonding applications.