Gas temperature measurement in CF4, SF6, O2, Cl2, and HBr inductively coupled plasmas

Abstract

Neutral gas temperature (Tg) is measured in an industrial high-density inductively coupled etch reactor operating in CF4, SF6, O2, Cl2, or HBr plasmas. Two laser diodes are used to deduce Tg from the Doppler widths of 772.38 and 811.5nm lines absorbed by Ar*(P23) metastable atoms, when a small amount of argon (5%) is added to the gas flow. With the 811.5nm beam passing parallel to the wafer, Tg near the wafer surface is obtained by laser absorption technique. With the 772.38nm beam entering the top of the reactor perpendicular to the wafer surface, the volume averaged temperature is deduced by laser induced fluorescence technique. The volume averaged Tg increases with radio frequency power and with pressure, although the temperature near the walls is only weakly dependent on gas pressure. The main effect of increasing the pressure is an enhancement of the temperature gradient between the discharge center and the wall boundary. Due to the thermal accommodation, the authors always observe a significant temperature jump between the surface and the gas in its vicinity. This gap is typically about 200K. Gas temperatures for a wide range of pressure and rf powers are reported. These data will be useful to validate and improve numerical models of high-density reactive plasmas.

Measuring ion velocity distribution functions through high-aspect ratio holes in inductively coupled plasmas

“…2, because this flux is obtained by integration of the IVDF and less sensible to noise. The measured T i ¼ 0.27 eV is far above the expected neutral temperature (<0.07 eV near the wafer 16 ), but it is in excellent agreement with ion temperatures measured in the high density plasma. 17 From a long set of experiments in various gases and rf power (not shown), we concluded that ions in ICP reactor operated in typical conditions have a temperature of about 2500-3000 K.…”

Density of atoms in Ar*(3p54s) states and gas temperatures in an argon surfatron plasma measured by tunable laser spectroscopy

“…With TDL off, I back ðÞ and I plasma ðÞ are recorded without and with plasma, respectively. So the spectral dependent absorbance 32…”

Characterization of silicon etching in synchronized pulsed plasma

“…Gas heating is basically reduced due to a lower average source power in pulsed mode. Assuming that H and H 2 have a similar density to Br and Br 2 , respectively, and neglecting O-containing species, we can estimate the plasma temperature around 650 K in CW mode, consistent with the literature [11]. The temperature decreases and is expected to tend towards 330 K at very small duty cycle.…”