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▲ [20a-H103-1] Diamond growth perturbed by high TMB partial pressures
Keywords:diamond,plasma
The chemistry that supports diamond boron doping by microwave plasma-activated chemical vapor deposition (MPCVD) is complex, but its understanding is required for the sake of reproducible sample preparations. In many studies, diborane (B2H6) or trimethylboron (B(CH3)3, TMB) diluted in hydrogen (H2) are used as boron source, and methane (CH4) as carbon source. Therefore, boron precursors are converted into active species typ. BHx (x = 0–3) by the plasma. Some of those BHx accommodate into the growing diamond film by mean of surface reactions. Here, optical emission spectroscopy (OES) has been used to monitor in-situ the deviation of relative densities of BH, H, and C2 radicals close to the diamond surface as functions of process conditions.
In the particular diamond growth with a CH4 partial pressure below 2 % and the admixture of TMB, we found some differences in the relative density of active species from models. In this study, the transition from growth to etching has been revealed when more than 0.5 % of TMB were introduced in the plasma. The OES of etchant plasma conditions showed a variation of its chemical composition, essentially concerning the production of BH radicals. The production of larger amount of BH species was investigated by increasing microwave power, gas pressure and under several CH4/H2 ratio.
In the particular diamond growth with a CH4 partial pressure below 2 % and the admixture of TMB, we found some differences in the relative density of active species from models. In this study, the transition from growth to etching has been revealed when more than 0.5 % of TMB were introduced in the plasma. The OES of etchant plasma conditions showed a variation of its chemical composition, essentially concerning the production of BH radicals. The production of larger amount of BH species was investigated by increasing microwave power, gas pressure and under several CH4/H2 ratio.