Low Temperature SLID Bonding Approach in Fine Pitch Chip-stacking Structure with 30 μm-pitch Interconnections

抄録

In this study, a 160°C low-temperature bonding method was developed for fine pitch chip-stacking application by Solid-Liquid Inter-diffusion (SLID) bonding technology. The chip-to-wafer test was conducted by using Cu/Sn-Ag and Cu/Ni/In as the micro pillar bump structure for top chip and bottom wafer, respectively. Indium, with a low melting point of 157°C, was chosen to realize the SLID bonding mechanism in this study. A thin indium layer with a thickness of 1 μm was plated on nickel to induce low temperature bonding with tin. These 30 μm-pitch interconnects bonded at low temperature were well-bonded and exhibited excellent electrical continuity through 3,264 I/Os. Furthermore, the bonded samples were tested under reliability assessments to verify the thermal stability.