PREPARATION OF WSI2 BY RAPID THERMAL ANNEALING OF CVD THIN-FILMS OF TUNGSTEN

Tungsten silicide (WSii) films were prepared by rapid thermal annealin g (RTA) of W films obtained by chemical vapor deposition (CVD) from ca rbonyl precursor-W(CO)(6). The RTA process proceeds at 800-1400 degree s C in different gas environments-argon, nitrogen, vacuum, etc. Invest igations of the crystal phase structure were performed by Reflection H igh Energy Electron Diffraction (RHEED) method. Difference in the phas e composition was observed for ''thin'' and ''thick'' WSi2. Close to t he surface of W films, a pure metal rich phase is formed, and at the i nterface W/Si, a phase rich of Si is found. Diffusion was considered t o be the controlling process in the kinetics formation of WSi2. The in fluence of the gas environment on WSi2 was also studied. The compariso n made shows that nitrogen favours WSi2 formation. Some of the samples have shown a certain degree of texturing. (C) 1998 Elsevier Science L td All rights reserved.