AN INVESTIGATION OF THE STABILITY OF COPPER GERMANIDE THIN-FILMS IN THE PRESENCE OF SI AND SIO2

Copper germanide (Cu3Ge) has received interest in recent years as a potential metallization for VLSI applications due to its exceptionally low room temperature resistivity. We have investigated the thermal stability of Cu3Ge thin films on both silicon and thermally oxidized silicon wafers. Films were deposited by electron beam evaporation of sequential layers of Ge and Cu and exposed to an annealing schedule ranging from 100 degrees C to 450 degrees C. Secondary ion mass spectrometry (SIMS) analysis has revealed an interaction of the film with the silicon substrate. At temperatures as low as. 200 degrees C, diffusion of silicon into the copper germanide film was observed with the concentration and depth of penetration scaling with increased annealing temperature. Results on controlling this interaction will also be presented and correlation is made with resistivity measurements.