AVS 47th International Symposium
    Plasma Science and Technology Thursday Sessions
       Session PS2-ThM

Paper PS2-ThM2
Diagnostics of Inductively Coupled Chlorine Plasmas: Measurements of the Neutral Gas Temperature

Thursday, October 5, 2000, 8:40 am, Room 311

Session: Plasma Diagnostics II
Presenter: V.M. Donnelly, Bell Laboratories, Lucent Technologies
Authors: V.M. Donnelly, Bell Laboratories, Lucent Technologies
M.V. Malyshev, Bell Laboratories, Lucent Technologies
Correspondent: Click to Email
We report measurements of the bulk, neutral gas temperature in a chlorine inductively coupled (ICP), or transformer-coupled plasma (TCP). A trace amount (2-5%) of N@sub 2@ was added to the discharge and the rotational temperature of the C-state was determined from the C->B emission in the ultraviolet. This temperature has been shown by others to be equal the rotational temperature of ground state N@sub 2@, which is the thermally equilibrated (translational and rotational) gas temperature (T@sub g@). The gas temperature 3 cm above the wafer is equal to, or only slightly above the wall temperature (300 K) throughout the low-power, capacitively-coupled regime (<60 W, 0.024 W/cm@super 3@). Between the lowest (130 W, 0.053 W/cm@super 3@) and highest (900 W, 0.36 W/cm@super 3@) inductively-coupled mode powers investigated, T@sub g@ increases sub-linearly with power (and electron density). At the high-power (900 W), T@sub g@ increases with increasing pressure (650, 750, 900, and 1250 K at 2, 5, 10 and 20 mTorr, respectively). These measurements will be contrasted with those made in an Ar plasma. Briefly, much lower temperatures are found in Ar plasmas of similar power densities and electron densities. Mechanisms of neutral gas heating will be discussed. The energy released in dissociation of Cl@sub 2@ appears to be the dominant heating mechanism in a chlorine plasma. Implications of neutral gas heating in high-density plasmas will also be discussed. Heating of the gas at high powers causes the gas number density to decrease, and correspondingly leads to an increase in the electron temperature.