Investigation and modeling of plasma-wall interactions in inductively coupled fluorocarbon plasmas

Plasma-wall interactions in fluorocarbon based feedgas chemistries, namely CF4, are examined in a standard inductively coupled Gaseous Electronics Conference reference cell using in situ Fourier-transform infrared spectroscopy and microwave interferometry. Measurements show the dissociation of the CF4 feedgas into radical CF, species, as has been observed elsewhere [M. J. Goeckner and R. A. Breun, J. Vac. Sci. Technol. A 11, 3 (1993)], and qualitatively reveal a decrease in plasma-wall interactions as wall temperature is increased. Experimental results such as plasma density, loll cm(-3), and CF4 density 10(13) cm(-3), are further compared to results from the hybrid plasma equipment model [R. Kinder and M. J. Kushner, J. Vac. Sci. Teclulol. A 19, 76 (2001)] to better elucidate the influence of wall temperature on plasma exposed surfaces and sticking coefficients. Last, CF4 vibrational temperatures were also measured, revealing that the line-averaged vibrational temperature remains at a constant 40-60 K above the chamber wall temperature while the vibrational temperature in the center of the discharge is significantly higher. Moreover, the vibrational temperatures are further compared to results from a global thermal model and are in good agreement. (C) 2004 American Vacuum Society.