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Surface studies of amorphous W/sub 75/Si/sub 25/ oxidation

Journal Article · · J. Vac. Sci. Technol., A; (United States)
DOI:https://doi.org/10.1116/1.576071· OSTI ID:6338378
The surface composition and oxide growth kinetics of amorphous W/sub 75/Si/sub 25/ sputter-deposited thin films were examined using x-ray photoelectron spectroscopy (XPS), ellipsometry, and thermogravimetric analysis (TGA). These films have been proposed as metallization layers on compound semiconductors for high-temperature applications. The 1-..mu..m-thick films were oxidized in air at temperatures of 30 to 600 /sup 0/C for times of 10 min to 30 h. Angle resolved XPS measurements indicated that the surface region consisted of a thin layer (/similar to/16 A) of primarily SiO/sub 2/ above a layer of mainly WO/sub 3/ for oxidation temperatures up to 425 /sup 0/C. At oxidation temperatures between 150 and 425 /sup 0/C the WO/sub 3/ signal from the surface region was enhanced. In this range the SiO/sub 2/ layer was thinner resulting in a larger detected signal from the underlying WO/sub 3/ layer. For oxidation temperatures above 450 /sup 0/C, the two oxides appeared to coexist although the surface region was enhanced in SiO/sub 2/. Ellipsometry and TGA measurements did not indicate a change in oxide growth kinetics in the temperature range 150--550 /sup 0/C. The kinetics were parabolic and displayed an Arrhenius-type temperature dependence with rates similar to W oxidation.
Research Organization:
Sandia National Laboratories, Albuquerque, New Mexico 87185
OSTI ID:
6338378
Journal Information:
J. Vac. Sci. Technol., A; (United States), Journal Name: J. Vac. Sci. Technol., A; (United States) Vol. 7:3; ISSN JVTAD
Country of Publication:
United States
Language:
English