Au-Al Solid Phase Diffusion Flip Chip Bonding -Desirable Composition of Au-Al Intermetallic Compound for Stable Bonding-

摘要

A gold-aluminum (Au-Al) solid phase diffusion flip chip bonding has been developed. In this technique, the Au bumps on the LSI are bonded directly to the Al wiring on the glass substrate by formation of a Au-Al diffusion layer. This paper reports on dependence of reliability on the bonding temperature and Al layer thickness, and analyses of interfaces produced. The results confirm that it is possible to achieve initial electric contact. Au4Al, Au5Al2, Au2Al and AuAl2 are generated between Au bump and Al wiring. The difference in composition of the intermetallic layer contributes to the bonding reliability. When the Au4Al content is the highest, a highly reliable bonding is obtained.