FORMATION OF Cu-Au INTERDIFFUSION BARRIER BY C+ IMPLANTATION
Original Publication Date: 1989-Oct-01
Included in the Prior Art Database: 2005-Jan-29
The Cu-Au thin film structure is widely used in contact metallurgy, with Cu providing conduction and Au for the protection of Cu against environmental corrosion and oxidation. However, even at relatively low temperatures, 200-300oC, severe interdiffusion of Cu and Au takes place. This changes the electrical and the metallurgical properties of each metal so that Au no longer provides any protection for Cu. In packaging technology, where Au also provides good bonding properties for joints, Cu diffusion into Au reduces the rework capability of the Au. Ni or Co layers are commonly used to control interdiffusion of Cu-Au, but Cu diffuses through these layers into Au irrespective of their thickness 1.