Methyl radicals (CH 3) and positive ionic species in a low-pressure inductively coupled plasma under diamond-depositing conditions have been detected by using a quadrupole mass spectrometer. Absolute calibration of the fluxes of CH 3 and ionic species was made by the threshold ionization technique and Langmuir probe measurement, respectively. The CH 3 density increased by two to three times with a small addition of carbon monoxide to a methane-hydrogen plasma and was on the order of 10 11-10 12 cm -3. As the pressure decreased from 60 to 10 mTorr, the ion-to-CH 3 flux ratio increased from 0.2 to 4.3, accompanied by an increase in the fraction of light ions such as H x + (x=1-3). The average ion energy in the ion energy distribution at a grounded electrode was compared with the sheath potential and the discrepancy was found to be 0.5-2 eV depending on pressure and ion mass. The results were used to describe the specific surface process dominated by energetic (∼ several eV) ions rather than thermal neutrals.
All Science Journal Classification (ASJC) codes
- Physics and Astronomy(all)