Plasma-enhanced atomic layer deposition of tungsten nitride

Tungsten nitride (WN) has potential as an interconnect barrier film. Deposition of WN films with bis(tert-butylimido)bis(dimethylamido)tungsten utilizing plasma-enhanced atomic layer deposition has been investigated over a temperature range of 100–400 ° C employing N 2 , H 2 / N 2 , and NH 3 remote plasmas. Spectroscopic ellipsometry has been used to determine film thickness and optical properties. Film growth rate varied from 0.44 to 0.65 Å / cycle . Chemical composition was investigated with x-ray photoelectron spectroscopy. W:N ratios varied from 0.95:1 to 3.76:1 and carbon levels were sub-2% for atomic layer deposition conditions. Resistivity measurements, derived from four-point probe measurements, indicate higher deposition temperature and gas flow rates produce the lowest resistivity films. The lowest resistivity film of the study, which measured 405 μ Ω cm , was deposited with a hydrogen-rich H 2 / N 2 plasma at 400 ° C .