SPUTTERED TUNGSTEN FOR DEEP SUBMICRON COMPLEMENTARY METAL-OXIDE SEMICONDUCTOR TECHNOLOGY

Tungsten gate metal-oxide-semiconductor capacitors formed by 6.5 nm of thermal SiO2 and 150 nm of sputtered tungsten have been characterized. The gate metal was deposited using high argon pressure (55 m Torr) 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-degrees-C less-than-or-equal-to T less-than-or-equal-to 800-degrees-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 greater-than-or-equal-to 700-degrees-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.