Sputtered tungsten for deep submicroncomplementary metal-oxide-semiconductor technology

Abstract

Tungsten gate metal-oxide-semiconductor capacitors formed by 6.5 nm ofthermal SiO2 and 150 nm of sputtered tungsten have been characterized. The gate metal was deposited using high argon pressure (55 mTorr) to obtain a deposit with a low residual internal stress. To avoid tungsten oxidation and to remove the oxide damage caused by the sputtering deposition process, thermal treatments (500°C ≤ T ≤ 800°C) were performed in a silicide oxygen-free furnace. The electrical characterization has shown the efficacy of the low temperature anneal and the onset of gate oxide degradation on treatments at T ≥ 700°C. There is experimental evidence that this degradation can be attributed, at least partially, to the oxygen depletion that characterizes the environment inside the silicide anneal furnace. © 1990 Elsevier Sequoia S.A.