Hybrid Au-Au bonding technology using planar adhesive structure for 3D integration

This paper describes the hybrid Au-Au bonding technology in which the Au-Au and adhesive-adhesive bonding are carried out simultaneously using planar adhesive structure for 3D integration. The planar adhesive structure was fabricated by CMP of adhesive, and consists of ultralow-profiled Au bump with flat surface and uncured adhesive. The bonded interface was observed with SAM and SEM. The results indicate that Au bump connection and the adhesive filling of the 6-μm gap between bonded chip and substrate were achieved without significant void. All 900 bumps were also electrically connected. Furthermore, the shear strength of the bonded sample was13 MPa. The adhesive was strongly bonded because the Si substrate of bonded sample was broken to pieces.