TEMPERATURE-DEPENDENCE OF ATOMIC MIXING AT THE COPPER-SILICON INTERFACE

The atomic mixing and formation of silicides during deposition of a th in film onto a substrate are caused by diffusion processes which are d ominated by thermal effects and are also influenced by the energy of t he incident particles. Sputter deposition of metal thin films on a sil icon substrate shows the formation of silicides at the interface of me tal and silicon. This is particularly marked in the case of copper thi n films deposited onto silicon. In this paper, the influence of the su bstrate temperature on broadening of the mixed layer at the interface is discussed and experimental results are presented. The mixing profil es and the compositions of the silicides near the interface are evalua ted using Rutherford backscattering spectroscopy. The experimental res ults show that sputter deposition at a temperature below 550 K causes moderate interfacial mixing (the silicide thickness is about a few ten s of nanometres) while at comparatively higher temperatures the interm ixed layers are broadened to more than 200 nm.