Hybrid Surface Treatment for Copper-to-Copper Thermal Compression Bonding Thermal Compression Bonding

3D IC integration becomes one of the important trends in microelectronics manufacturing, and direct Cu bonding is considered an ideal way to achieve inter-chip vertical connections for TSV (through silicon via), due to size miniaturization and low electrical resistance. In this study, plasma was adopted to modified copper surface, and the effect of a subsequent light exposure was systematically investigated. Experimental results reveal that plasma bombardment contributed to a higher joint strength, which can be referred to an increase in compressive stress component and thus reduced tensile residual stress for copper surface, thereby led to an accelerated self-diffusion and improved bonding strength. If flash irradiation was applied following plasma treatment, bonding performance can be further enhanced.