Cu Thickness Effects on Bonding Characteristics in Cu-Cu Direct Bonds

Cu-Cu thermo-compression bonding process was successfully developed as functions of the deposited Cu thickness and 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 interfacial toughness was measured by 4-point bending test. Pre-annealing with gas at is effective to achieve enough interfacial adhesion energy irrespective of Cu film thickness. Successful Cu-Cu bonding process achieved in this study results in delamination at interface rather than Cu/Cu interface.