Microstructure analysis and tensile strength of low temperature Cu bonds using highly-<111> Cu

This investigation shows bonding strength improvement by adjusting the microstructures in the Cu joints. The Cu pad used in this investigation is nanotwinned Cu pad with surface ratio more than 95% <111> preferred oriented. Result showed that bonding strength can be obtained in low temperature and pressure applied and short time during bonding process. Once the bonding time or pressure increases, recrystallization and grain growth triggered. By adjusting bonding time or bonding temperature, the microstructure in Cu pad can be controlled thus the bonding strength can be improved by adjusting microstructures in the Cu pads.