Characterization of an ECR etching plasma with a microwave interferometer, Langmuir probes and a FTIR

Summary form only given. The authors have partially characterized an ECR (electron cyclotron resonance) etching device by using a microwave interferometer in the source region and Langmuir probes and an FTIR (Fourier transform infrared) in the downstream target region. The microwave interferometer gives a measure of the line averaged density in the source and is present for all the measurements. For a given set of conditions, the Langmuir probes are used to measure the plasma density and electron temperature radial profiles in the downstream region. The FTIR monitors the neutral gas concentration of the etching feed gas, CF/sub 4/. The interferometer is used to cross check that the conditions are similar. With the feed gas in the source region, the line averaged plasma at 10/sup 12/ cm/sup -3/, and neutral pressure below 2 mTorr, a significant fraction (80%) of the CF/sub 4/ feed gas is `burned out´ by the plasma. This fraction varies with the neutral pressure, gas flow rate, and plasma density. This is consistent with a 2-D plasma-`chemistry´ code developed to model this ECR system. The code predicts that varying the feed gas location should also vary the neutral composition.