Effect of wet pre-treatment on interfacial adhesion energy of direct Cu-Cu bond

Abstract

Cu and Ti films were deposited by sputtering on thermally oxidized Si wafers and then the deposited films were bonded by direct Cu-Cu thermo-compression bonding for evaluating the effect of the wet pre-treatment on the interfacial adhesion energy. The interfacial adhesion energy was evaluated as 0.29, 1.28, 1.64, 1.17, and 0.42 J/m2 by acetic acid pre-treatment at 35°C for 0, 1, 5, 10, and 15 min. The existence of optimum wet pretreatment time seems to be related to the film thickness effect as well as the surface oxide removal effect.