Plasma enhanced atomic layer deposition of molybdenum carbide and nitride with bis(<i>tert</i>-butylimido)bis(dimethylamido) molybdenum

Abstract

Molybdenum carbonitride films were deposited using plasma enhanced atomic layer deposition techniques with (tBuN)2(NMe2)2Mo at temperatures ranging from 80 to 300 °C. The elemental composition of the molybdenum carbonitride films were analyzed using x-ray photoelectron spectroscopy with a MoCxNy composition extending from carbide, MoC0.45N0.08 to nitride MoC0.06N1.40 (x: 0.06–0.45; y: 0.08–1.40). The film composition, electrical properties, and optical properties are strongly dependent upon the % N2 in H2 of the plasma gas stream, as well as the process temperature. The molybdenum carbide film (MoC0.45N0.08) deposited at 150 °C achieved an electrical resistivity (ρ) value of 170 μΩ cm and exhibited superconducting behavior with a transition temperature (Tc) of 8.8 K. Nitrogen rich molybdenum carbonitride films (MoC0.28N0.44) deposited at 250 °C with 6% N2 in the plasma gas showed a microcrystalline fine grained structure with a measured ρ = 200 μΩ cm. Film thickness and optical properties were characterized using spectroscopic ellipsometry with a measured growth per cycle extending from 0.36 to 0.56 Å/cycle. The measured optical properties extend across a broad range; refractive index (n: 3.1–3.4), and dielectric constant (k: 1.5–3.18). Grazing incidence x-ray diffraction of the MoCxNy films indicate a fine grained crystal structure, with a transition from a cubic MoC1−x phase for the carbide to a face center cubic γ-Mo2N1±x phase for the nitride films.