Low temperature Cu/SiO2 hybrid bonding fabricated by 2-step process

In this investigation, die-to-die Cu/SiO2 hybrid bonding can be well bonded and obtain excellent bonding strength with Ar plasma pretreatment. The diameter of the microbumps is 8 μm along with 20 μm pitch. Results show that Cu joints can be well bonded under 150 °C ~ 200 °C for 1h in vacuum ambient after water fusion bonding followed by postbonding annealing at 175 °C~200 °C without any external pressure. Cross-sectional electron analysis shows no oxide bonding interface along 150 μm long and no gaps or cracks observed in Cu bonding. Bonding strength was measured by pull tests.