Chemical Reaction Mechanism in the Atomic Layer Deposition of TaCxNy Films Using tert-Butylimidotris(diethylamido)tantalum

Abstract

The gas phase and the surface reaction mechanism of tert-butylimidotris(diethylamido) tantalum involved in the atomic layer deposition of TaCxNy films were studied. A gas cell and a surface reaction cell with in situ Fourier transform infrared spectroscopy, along with a quadrupole mass spectrometer, were used to monitor the gas phase and surface decomposition of the precursor. The deposition rate per cycle as a function of the deposition temperature was measured. The phase composition of the film including TaC, TaN, and Ta3N5 deposited with atomic layer deposition using hydrogen with or without plasma was also measured. In situ diagnostic tools were effective in explaining the deposition behavior and the film composition. It was confirmed that Ta=N and N-C bonds in the precursor disappeared upon adsorption on the oxide surface even at room temperature. Atomic hydrogen dissociated the hydrocarbon species and enhanced the formation of the Ta-C bond. Due to the precursor dissociation, the deposition rate per cycle was increased with temperature above 350 degrees C, but with atomic hydrogen, the deposition rate stayed nearly the same due to the suppression of the film forming species. (C) 2010 The Electrochemical Society. [DOI: 10.1149/1.3377003] All rights reserved.