Low temperature chemical vapor deposition of superconducting molybdenum carbonitride thin films

Abstract

Thin films of molybdenum carbonitride, MoCxNy, are deposited by low temperature chemical vapor deposition from Mo(CO)6 and NH3 in the temperature range 150–300 °C. At a substrate temperature of 200 °C and Mo(CO)6 pressure of 0.01 mTorr, the composition varies from MoC0.48N0.20 to MoC0.36N0.33 (i.e., greater nitrogen and less carbon content) upon increasing the ammonia pressure from 0.3 to 3.3 mTorr. At a constant Mo(CO)6 pressure of 0.01 mTorr and an NH3 pressure of 2 mTorr, the composition varies from MoC0.50N0.30 to MoC0.12N0.40 with increasing substrate temperature from 150 to 300 °C. Selected films grown at substrate temperatures of 150, 200, and 250 °C are superconducting with critical temperatures of 4.7, 4.5, and 5.2 K, respectively. Grazing incidence x-ray diffraction data indicate that the films are crystalline and isomorphous with the cubic phases of Mo2N and Mo2C. With a forward-directed flux of precursors toward the surface, film growth is highly conformal in microtrenches of aspect ratio 6, with step coverages of ∼0.85 and 0.80 at growth temperatures of 150 and 200 °C, respectively.