Room temperature interdiffusion studies of Au/Sn thin film couples

Room temperature interdiffusion studies of Au/Sn thin film couples were made using transmission electron microscopy, X-ray diffraction and Rutherford backscattering techniques. Au/Sn thin film couples were found to interdiffuse at room temperature via both bulk and grain boundary diffusion mechanisms. In the bulk diffusion, gold diffuses interstitially into tin and initially forms AuSn 4 and AuSn intermetallic compounds. Grain boundary diffusion of tin into gold is also observed. The use of various thickness combinations in the thin film couples permitted detection of four intermetallics (ζ phase, AuSn, AuSn 2 and AuSn 4) which can form as a result of the interdiffusion. In addition, it was found that interdiffusion accompanied by the formation of hillocks and Kirkendall voids.