Cu to Cu direct bonding at low temperature with high density defect in electrodeposited Cu

Abstract

Using the high defect density Cu (HD2 Cu), successful Cu-Cu direct bonding was obtained at low temperature, 240 °C. In our previous research, the self-annealing mechanical properties of the HD2 Cu was studied on electrodeposited Cu. In this study, HD2 Cu grain growth behaviors for direct Cu-Cu bonding were investigated by various analytic methods. The effect of electrodeposition temperature was compared between room temperature and low temperature, 0 °C under high current condition. The HD2 Cu is more obtained at a low temperature than room temperature and their grains grew mainly according to the strain energy release. But normal temperature electrodeposited Cu dominated by surface energy has similar grain growth orientation to the Cu with additives. Grain growth behaviors with different grain orientation were observed in each case depending on different energy reduction. The HD2 Cu grains grew to the (1 0 0) orientation direction for the strain energy relaxation.