Gas temperature measurement in Ar and Ar-Cl2 based ICP discharge: Comparison between experiments and simulations

Summary form only given. Gas temperature is an important parameter for the study of discharge modeling and in plasma etching process. We present neutral gas temperatures in Ar and Ar-Cl₂ based ICP discharge measured by diode laser absorption spectroscopy (IRLAS) and Laser Induced Fluorescence (LIF) of argon metastable atoms. The temperature was deduced from the Doppler width of the 1s₅→2p₇ transition at 772.38nm. The line averaged temperature was determined by absorption spectroscopy, whereas the local gas temperature at the reactor centre was determined from the laser-excited 1s₄←2p₇ fluorescence at 810nm. The gas temperature was measured as a function of power (50-500W), pressure (5-90mTorr) and %Cl₂ in Ar (0-90%). In pure Ar the temperature increase with gas pressure and RF power, reaching 600K at 90mTorr 500W, whereas in 90% Cl₂ temperatures as high as 1500K were found. The results were compared to simulations using the Hybrid Plasma Equipment Model (HPEM)¹. The simulations indicated significantly lower temperatures than the experiment, which were furthermore independent of gas pressure (5-90mTorr) in Ar. Finally the electron density was also compared with the simulation results for same range of operating conditions.