FTIR measurements in an ICP etching plasma using CF/sub 4/

Summary form only given. Spectroscopic measurements using Fourier transform infra-red (FTIR) were made between 700 cm/sup -1/ and 4000 cm/sup -1/ in a magnetically confined inductively coupled plasma (MCICP) etching tool. The operating pressure range was 2-9 mTorr. The peak plasma density was of the order of 5/spl times/10/sup 11/ cm/sup -3/ (at 750 W), and extended over the inner 30 cm diameter of the 40 cm diameter vacuum system. The axial length of the source is 50 cm. The electron temperature is 2-3 eV. Two fluorocarbon gases have been studied so far. The breakup of the tetrafluoromethane (CF/sub 4/) parent gas was measured vs. power and pressure. The vibrational temperature of the parent gas was measured vs. Power between 500-1000 W and ranged between 315-350 K. The temperatures were slightly lower (10% lower at 1000 W) than previous results in an electron cyclotron resonance (ECR) etching tool. These results show that the rotational temperatures are close to the temperature of the vacuum walls. The MCICP has water cooled walls (/spl sim/25/spl deg/C). The ECR source chamber typically operates at 50-70/spl deg/C. Products of the CF/sub 4/ plasma discharge identified were SiF/sub 4/, CO, CO/sub 2/, and a fluorocarbon film that deposited on the windows. No substantial signal in the CF/sub 3/ absorption region was observed. The rotational temperature of CO was measured at 500 W and 1000 W (370 K and 383 K, respectively). Preliminary results were obtained using trifluoromethane (CHF/sub 3/) as the parent gas, where much more breakup of the parent gas was observed.