Synthesis of diamond films with reduced roughness in microwave plasma

The work studies the effect of nitrogen additions on the secondary nucleation (nucleation) of diamond during its synthesis by chemical vapor deposition (CVD). A series of polycrystalline diamond (PCD) films 2 μm thick were grown on silicon substrates in methane-hydrogen-nitrogen gas mixtures with different nitrogen concentrations (0–1%). The structure and roughness of the grown films were studied using scanning electron microscopy (SEM) and optical profilometry. It has been shown that small additions of nitrogen play a key role in the processes of secondary nucleation of diamond, having a significant impact on the morphology of films. The comparison of the characteristics of grown PCD allowed us to find the optimal nitrogen concentration [N2] ≈ 0.2% for the formation of nanocrystalline diamond (NCD) films with low surface roughness and increased growth rate. The results obtained are expected to be used to optimize the parameters of CVD synthesis of PCD films for use as protective or friction-reducing layers, as well as for the manufacture of superhard cutting tools.