The annealing effect on work function variation of WN_xC_y films deposited by remote plasma atomic layer deposition

Tungsten-nitrogen-carbide (WN_xC_y) thin films were investigated as the metal gate of complementary metal-oxide-semiconductor (CMOS) devices. WN_xC_y thin films were deposited by employing the remote plasma atomic layer deposition (RPALD) using a bis(tert-butylimido) bis (dimethylamido) tungsten (BTBMW) precursor and hydrogen plasma as a reactant. The growth rate of the WN_xC_y films was about 0.12 nm/cycle. X-ray diffraction (XRD) analysis indicated that the films consisted of a mixture of tungsten carbide and tungsten nitride phases. The atomic force microscope (AFM) analysis further confirmed that the WN_xC_y film surfaces deposited by RPALD were smooth. In addition, the chemical bonding state analysis showed that the WN_xC_y films consisted of WN, WC, and WO phases. To measure the work function of the WN_xC_y film, a MOSCAP (metal oxide semiconductor capacitor) stack was fabricated and the flat band voltage was measured by current-voltage (C-V) measurements. A WN_xC_y work function value of 4.91 eV was suitable for p-MOS and the work function of the WN_xC_y films varied depending on the annealing treatment, and was higher than the work function of the as-deposited WN_xC_y film. (copyright 2017 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)