AES determination of compositional variation in LPCVD tungsten silicide films in confined spaces

Abstract

AbstractCompositional variation in chemical vapor deposited tungsten silicide films in confined spaces has been studied using scanning Auger electron spectroscopy. ‘Infinitely’ long silicon trenches with aspect ratios ranging between 1.5 and 5 were used to define the confined space. Composition changes down the sidewall of a partially filled trench were determined by cleaving the sample along the length of a trench and analyzing specific points down the sidewall. The samples were lightly sputtered before analyzing to remove the native oxide and reach a uniform composition of the silicide. The sample was carefully positioned during sputtering to minimize any redeposition of material onto the analysis area due to sputtering of adjacent surfaces. Using this method the silicon content of the silicide was shown to increase as a function of distance from the surface. This spatial variation in film composition qualitatively agrees with the predictions of a computer simulation of the deposition process.