| Langmuir probe techniques and tunable infrared diode laser absorption spectroscopy were applied to a magnetically confined inductively coupled plasma (MCICP) etcher and an electron cyclotron resonance (ECR) etcher, respectively.; An improved Langmuir probe system was used to investigate the plasma potential, electron density, and electron temperature of Ar, O2, Cl2, and CF4 plasmas in the MCICP etcher. They were obtained at 500 W of 13.56 MHz RF power and 2 mTorr pressure 20 cm below the quartz window at 19 radial positions from −18 cm to +18 cm. Their radial uniformities are all better than 10% within a diameter of 20 cm. These parameter values can differ substantially with different wall conditions. The electron energy distribution function of electropositive Ar plasma was found to be different than those in the electronegative plasmas Cl2, O 2 and CF4 in the low energy region. Also the electron density and temperature in the atomic gas Ar show different trends with pressure variation than those in molecular gases N2, Cl2, and O2.; In the ECR etcher the equivalent width method, which is the most accurate one available, was used to determine the absolute densities of CF and CF 2 molecules in CF3H plasmas from diode laser direct absorption spectra. In a 10 mTorr, 1000 W CF3H plasma, the CF2 density was 5.6 × 1013 cm−3, and the CF density was 2.4 × 1012 cm−3. The CF and CF2 densities were found to increase with pressure at 1000 W. The CF2 density did not change much with power at 10 mTorr, while the CF density increased with power. The simpler peak fractional absorption method was applied to determine the CF, CF2, and CF4 absolute densities in CF3H, CF4, C2F 6, and C4F8/Ar at five input powers from 500 W to 1500 W and at five neutral pressures from 3 mTorr to 20 mTorr. No CF, however, was observed in CF4 plasmas. The CF2 densities and the CF4 densities were generally in the 1013 cm −3 range, while the CF densities were in the 1011 cm−3 range. |
