Contaminations and Impurities in DC Magnetron Sputtered WSix Films on SiO2

Abstract

In this study, dc magnetron sputtered WSix films are characterized with RBS, SIMS, and TEM techniques. The films are deposited in a Varian 3180 sputtering system with the conmag WSi target 91‐1209‐05. Contaminations emitting from the shutter and cavity shields in the deposition chamber are reduced with the application of particle getter (PG). RBS analysis shows the films to contain 1.1 at% Ar and 0.11 at% Mo impurities along with WSix and SiO2. SIMS mass spectra also reveal the presence of Mo in WSix layer. The Si to W ratio (Si/W) and at% Mo increase with target use. No significant changes in the Si/W are observed with annealing in the temperature regime 700 to 1000 °C. The sheet resistivity of the WSix films decreases with increasing RTA temperatures. The TEM and XRD results of as‐deposited samples show the films are amorphous and the annealed samples are polycrystalline with tetragonal WSi2 phase. The annealed samples show the presence of larger grains and increased precipitation of silicon within the film. The low sheet resistance (12.2 Ω/□), conductivity, stability, good uniformity, fine grains, and manageable stress for good adhesion makes WSix a promising gate electrode material for submicron CMOS technologies.