Self-consistent modeling of microwave activated N<sub>2</sub>/CH<sub>4</sub>/H<sub>2</sub> (and N<sub>2</sub>/H<sub>2</sub>) plasmas relevant to diamond chemical vapor deposition
Michael N. R. Ashfold, Yu. A. Mankelevich
Abstract
Abstract The growth rate of diamond by chemical vapor deposition (CVD) from microwave (MW) plasma activated CH 4 /H 2 gas mixtures can be significantly enhanced by adding trace quantities of N 2 to the process gas mixture. Reasons for this increase remain unclear. The present article reports new, self-consistent two-dimensional modeling of MW activated N 2 /H 2 and N 2 /CH 4 /H 2 plasmas operating at pressures and powers relevant to contemporary diamond CVD, the results of which are compared and tensioned against available experimental data. The enhanced N/C/H plasma chemical modeling reveals the very limited reactivity of N 2 under typical processing conditions and the dominance of N atoms among the dilute ‘soup’ of potentially reactive N-containing species incident on the growing diamond surface. Ways in which these various N-containing species may enhance growth rates are also discussed.