SIMULATION AND EXPERIMENTAL-STUDY OF REEMISSION DURING SPUTTER-DEPOSITION OF TI-W FILMS

We used experiments and physically based process simulations to study the re-emission of Ti and W during sputter deposition of Ti-W films an d Ti during the sputter deposition of Ti films. Ti-W thin films have p reviously been shown to become Ti rich in geometrically confined areas , such as in features of a microelectronic device, compared to unconfi ned areas. This spatial composition variation was attributed to re-emi ssion of Ti during the deposition process. Re-emission during Ti-W spu tter deposition was confirmed by depositing a Ti-W film onto test stru ctures with large areas with no direct line-of-sight to the target. Tr ansmission electron microscopy was used to image the film deposited on all areas of the structure and Auger electron spectroscopy was used t o determine the composition of the film. EVOLVE, a physically based pr ocess simulator, was used along with the experimental data to estimate the effective sticking coefficients of Ti and W during Ti-W depositio n. Simulation results indicate the effective sticking factors of Ti an d W to be 0.30 and 0.74, respectively. The Ti to W effective sticking factor ratio determined in this study, 0.40, was in good agreement wit h that previously reported, 0.38. In comparison, sputter deposition of Ti onto these test structures showed little re-emission. Process simu lation of Ti sputter deposition indicated the Ti effective sticking fa ctor to be essentially unity. (C) 1996 American Vacuum Society.