Atomic Layer Deposition of Molybdenum Carbide Thin Films

The development of deposition processes for metal carbide thin films is rapidly advancing, driven by their potential for applications including catalysis, batteries, and semiconductor devices. Within this landscape, atomic layer deposition (ALD) offers exceptional conformality, uniformity, and thickness control on spatially complex structures. This paper presents a comprehensive study on the thermal ALD of MoC_x with MoCl₅ and 1,4-bis(trimethylgermyl)-1,4-dihydropyrazine [(Me₃Ge)₂DHP] as precursors, focusing on the functional properties and characterization of the films. The depositions are conducted at 200–300 °C and very smooth films with RMS Rq ≈0.3–0.6 nm on Si, TiN, and HfO₂ substrates are obtained. The process has a high growth rate of 1.5 Å cycle⁻¹ and the films appear to be continuous already after 5 cycles. The films are conductive even at thicknesses below 5 nm, and films above 18 nm exhibit superconductivity up to 4.4 K. In lieu of suitable references, Raman modes for molybdenum carbides and nitrides are calculated and X-ray diffraction and X-ray photoelectron spectroscopy are used for phase analysis.