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 po tential metallization for VLSI applications due to its exceptionally l ow room temperature resistivity. We have investigated the thermal stab ility of Cu3Ge thin films on both silicon and thermally oxidized silic on wafers. Films were deposited by electron beam evaporation of sequen tial 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 silico n substrate. At temperatures as low as. 200 degrees C, diffusion of si licon into the copper germanide film was observed with the concentrati on and depth of penetration scaling with increased annealing temperatu re. Results on controlling this interaction will also be presented and correlation is made with resistivity measurements.