Correlation between the OES plasma composition and the diamond film properties during microwave PA-CVD with nitrogen addition

The mechanisms of nitrogen incorporation in diamond are still an unsolved r iddle. This is mainly due to the complexity of the processes involved as th ey not only depend on empirical parameters (e.g. vessel pressure, substrate temperature, the gas phase composition, type and concentration of the nitr ogen containing compound used), but also on the plasma chemistry and the su rface chemical reactions. In this study, small quantities (ppm range) of di atomic nitrogen are added to a conventional hydrogen-methane feed gas mixtu re in order to investigate the effect of nitrogen incorporation in diamond films prepared by microwave plasma assisted chemical vapour deposition (CVD ). Optical emission spectroscopy (OES) is used to survey the plasma composi tion during deposition. The intensities of the CN, CH and C-2 emitting radi cals and the Balmer atomic hydrogen emission lines are correlated to the Ra man film quality and to the nitrogen content in the film measured by second ary ion mass spectrometry (SIMS). (C) 1999 Elsevier Science S.A. All rights reserved.