Plasma-enhanced atomic layer deposition of molybdenum carbide and carbonitride films using bis(isopropylcyclopentadienyl)molybdenum(IV) dihydride and an H2/N2/Ar plasma

Abstract

Molybdenum carbide (MoC) and molybdenum carbonitride (MoCN) films were successfully deposited by plasma-enhanced atomic layer deposition (PEALD) using bis(isopropylcyclopentadienyl)molybdenum(IV) dihydride [(iPrCp)2MoH2] as the Mo precursor at temperatures of 200−400 °C. To obtain the MoC and MoCN films, 4%H2/96%Ar (H2/Ar) and 4%H2/96%N2 (H2/N2) plasmas were selectively used as co-reactants, respectively. PEALD MoC and MoCN exhibited atomic layer deposition temperature windows of 200−400 and 250−300 °C with growth per cycle of 0.012 and 0.047 nm/cycle, respectively. X-ray photoelectron spectroscopy revealed that the 300 °C-grown MoC film prepared using an H2/Ar plasma contained Mo–C bonds and an atomic composition of MoC0.77. In contrast, the 300 °C-grown MoCN film prepared using an H2/N2 plasma exhibited Mo–C and Mo–N bonds, with an atomic composition of MoC0.31N0.23. The atomic composition of the PEALD MoCN films varied depending on the deposition temperature; at 200 °C, the carbon-rich MoC0.52N0.16 film was obtained, whereas the MoC0.23N0.23 film with a carbon-to-nitrogen ratio of 1 was grown at a higher temperature of 400 °C. The 300 °C-grown MoC film was crystallized into a cubic δ-MoC phase, whereas the PEALD MoCN film showed diffraction peaks corresponding to the hexagonal MoC and molybdenum nitride (MoN) structures. The as-deposited PEALD MoC and MoCN films at 300 °C exhibited resistivities of 600 and 3038 μΩ cm, respectively, and post-deposition annealing at 700−800 °C resulted in significantly low resistivities of 37−203 μΩ cm due to the formation of metallic Mo films.