Optical emission spectroscopy of the plasma during microwave CVD of diamond thin films with nitrogen addition and relation to the thin film morphology

Abstract

It is common knowledge that the presence of gas impurities such as nitrogen during microwave plasma assisted chemical vapour deposition of diamond can drastically affect the film morphology and even favour the growth of oriented textured films. it was shown previously that diamond films could be grown with various preferred orientations depending on the fraction of nitrogen present in the process gas mixture. In this work, we show how the methane and nitrogen fractions in the feed gas can alter the morphology of the diamond film deposited at high substrate temperature (1600 K). The domain of high substrate temperatures (>1300 K) has not yet been widely investigated and offers the opportunity of growing diamond films with other textures and morphologies with respect to their counterparts grown at lower temperatures. Optical emission spectroscopy is applied to study the spatial distribution of atomic hydrogen, CN and Ca emitting radicals from the substrate surface to the bulk plasma. Scanning electron microscopy and X-ray diffraction are used, respectively, to identify the different diamond film morphologies and to establish the preferred growth orientations ranging from {111} to {100} textured films. (C) 1997 Elsevier Science S.A.