Growth of ZrC thin films by aerosol-assisted MOCVD

Thin films of zirconium carbide (ZrC) have been grown on Si(1 1 1) substrates in the temperature range 400–600 °C by aerosol-assisted metalorganic chemical vapor deposition (AA-MOCVD) from tetraneopentylzirconium (ZrNp4) in benzonitrile (PhCN). Preliminary equilibrium calculations suggested that a minimal level of H2 was needed to prevent codeposition of solid carbon, and the minimum level decreased with decreasing temperature. Films were grown at different values of temperature, pressure, and H/Zr inlet molar ratio, as well as carrier gas (H2, He, or N2), and were judged by their X-ray diffraction (XRD) patterns to be amorphous. The trends in the measured composition (Auger electron spectroscopy, AES) of each film were qualitatively consistent with those of the equilibrium calculation, while X-ray photoelectron spectroscopy (XPS) analyses confirmed the formation of Zr–C and Zr–O bonds. It was not possible to grow films in N2 carrier gas or using tetrabenzylzirconium (ZrBn4). The results of density functional theory (DFT) calculations on ZrNp4 and ZrBn4 supported this latter result.