Gas-phase studies in inductively coupled fluorocarbon plasmas

Quantitative results from infrared laser absorption spectroscopy (IRLAS) of CF and CF, radicals and COF2 products in inductively coupled plasmas fed w ith C2F6, CHF3 and C4F8 are presented and compared with results simultaneou sly obtained by mass spectrometry and optical emission spectroscopy. These plasma gas-phase analysis results are discussed and compared to fluorocarbo n deposition and etching rates resulting from plasma-surface interaction,, at the Substrate. It is found that COF2 species are being formed (1) during O-2 plasma cleaning of a fluorocarbon contaminated reactor and (2) during SiO2 etching in fluorocarbon plasma,,, which in this work Occurred at the q uartz coupling window as a result of capacitive coupling between the induct ion coil and the plasma. IRLAS results on CF and CF2 densities are compared to fluorocarbon deposition and etching rates and it is found that low CF a nd/ or CF2 density does not necessarily translate into a low fluorocarbon d eposition rate. A relatively high deposition rate can be achieved at condit ions with a high ion current density and low CF and CF2 densities. (C) 2001 American Vacuum Society.