Fabry–Perot interferometry for magnetron plasma temperature diagnostics

Abstract

A confocal Fabry–Perot interferometer was utilized to study Ar–Ti, Ar–Cu and Ar–Cr dc magnetron discharges during sputtering of the corresponding metallic targets. Doppler broadening of Ar and Ti emission lines was measured in the wide range of Ar pressures and at different powers applied to the discharge. Spatial characterization of Ar and Ti line broadening through the discharge volume was also performed. Corresponding temperatures of Ar and thermalized Ti atoms were determined by Doppler broadening of the corresponding emission lines. Results show that the Ar temperature depends mainly on the working pressure in the reactor and it was found to be on average in the range 700–1300 K for the working pressure range 2–240 mTorr. The temperature of Ti was found to be about 600–800 K; it slightly increases with increasing applied power and does not depend on the working pressure in the reactor. Ar temperature measurements were verified by adding nitrogen in the discharge and by the measuring of the N2(C, v′ = 0 − B, v″ = 2) vibrational band shape.