An investigation was made of diffusion in wafers at 1200C. The wafers of Czochralski-type material had a Ni film on one surface and were mechanically damaged on the other surface. They were annealed in various ambients. It was found that, when the wafers were annealed in vacuum, a Ni-rich liquid phase formed at the opposite surface. The quantity of liquid phase increased with increasing annealing time. After cooling, the solidified material exhibited various morphologies, including dendrites and terraces. The thermodynamic driving force for these was suggested to be the Si surface free energy.

J.Li, W.S.Yang, T.Y.Tan, S.Chevacharoenkul, R.Chapman: Journal of Applied Physics, 1992, 71[1], 196-203