Thermal stability and oxidation resistance of W, TiW, W(N) and TiW(N) thinfilms deposited on Si

The thermal stability and oxidation resistance of similar to 100-nm-thick W , TiW, W(N) and TiW(N) thin films deposited on Si substrate by rf magnetron sputtering were investigated by X-ray diffraction, resistivity measurement , X-ray photoelectron spectroscopy, Auger electron spectroscopy and scannin g electron microscopy. All films showed good thermal stability against rapi d thermal annealing in nitrogen (RTN) at 800 degreesC for 1 min, except the W(N) film which decomposed to W and N-2 at 800 degreesC. The films also ex hibited differences in oxidation resistance against rapid thermal annealing in oxygen (RTO). Both W and W(N) films were significantly oxidized at temp eratures above 450 and 500 degreesC, respectively, while TiW and TiW(N) fil ms showed much better oxidation resistance up to temperatures of 750 and 65 0 degreesC, respectively. In general, nitridized films, i.e., W(N) and TiW( N), exhibit better resistance against oxidation than metallic films. Howeve r, TiW films exhibit better oxidation resistance than nitridized films at R TO temperatures greater than or equal to 600 degreesC due to a change in su rface oxide formation from a uniform oxide to a Ti-rich oxide. Once the fil ms were completely oxidized, they were peeled off.