Ambient dependence of metal diffusion through a less-electronegative metal layer

Abstract

The diffusion of metals through a less-electronegative metal layer is studied for its dependence on ambient gases. When the diffusion is essentially one directional with little interdiffusion, the observed ambient dependence is in agreement with that described by the surface potential model proposed earlier. An enhanced diffusion is expected when the ambient increases the work function of the less-electronegative metal through which the diffusion of the more-electronegative one is studied. This has been observed for the diffusion of Au and Cu across the intermediate Ni layer in the Au/Ni/Cu structure under both oxygen and hydrogen, and for the outdiffusion of Cu through Ni in the Ni/Cu structure by oxygen.