Effect of $N_2+H_2$ Forming Gas Annealing on the Interfacial Bonding Strength of Cu-Cu thermo-compression Bonded Interfaces

Cu-Cu thermo-compression bonding process was successfully developed as functions of the forming gas annealing conditions before and after bonding step in order to find the low temperature bonding conditions of 3-D integrated technology where the quantitative interfacial adhesion energy was measured by 4-point bending test. While the pre-annealing with gas below is not effective to improve the interfacial adhesion energy at bonding temperature of , the interfacial adhesion energy increased over 3 times due to post-annealing over after bonding at , which is ascribed to the effective removal of native surface oxide after post-annealing treatment.