AVS 46th International Symposium
    Plasma Science and Technology Division Tuesday Sessions
       Session PS-TuA

Paper PS-TuA8
Characterization of Transformer Coupled Oxygen Plasmas by Trace Rare Gas-Optical Emission Spectroscopy and Langmuir Probe Analysis

Tuesday, October 26, 1999, 4:20 pm, Room 609

Session: Plasma Diagnostics II
Presenter: N.C.M. Fuller, Bell Laboratories, Lucent Technologies and Columbia University
Authors: N.C.M. Fuller, Bell Laboratories, Lucent Technologies and Columbia University
M.V. Malyshev, Bell Laboratories, Lucent Technologies
V.M. Donnelly, Bell Laboratories, Lucent Technologies
I.P. Herman, Columbia University
Correspondent: Click to Email
Trace rare gas-optical emission spectroscopy (TRG-OES) and Langmuir probe analysis have been used to measure the electron temperature, T@sub e@, in a high-density inductively (transformer) coupled (TCP) 10 mTorr oxygen plasma as a function of the 13.56 MHz radio frequency (rf) power. Rare gas actinometry and modeling at 7774 and 8446 Å have been used to determine the absolute densities of ground state atomic and molecular oxygen and the O(@super 1@D), O(@super 1@S) and O@sub 2@(a @super 1@@delta@@sub g@) metastables in the plasma. In the bright (inductive) mode, T@sub e@ increases from 2.7 to 3.4 eV for the electrons sampled by the Langmuir probe and from 4.1 to 5.5 eV for the high energy electrons sensed by TRG-OES, as rf power is increased from 100 to 1046 W. In the dim (capacitive) mode, below 45 W, T@sub e@ increases from a few eV at very low rf power to ~ 6 eV at 45 W. T@sub e@ decreases from 4.5 ± 1.5 eV at ~ 45 W to ~ 3.3 ± 0.8 eV at ~ 100 W. The gas dissociation peaks at ~ 40% at the maximum rf power density of 5.7 Wcm@super -2@ (1046 W), for which the ground state atomic and molecular oxygen concentrations are 2.5 x 10@super 14@ cm@super -3@ and 3.9 x 10@super 13@cm @super -3@ respectively. At this power density, the densities of O(@super 1@D) and O(@super 1@S) are 2.0 x 10@super 13@ cm-3 and 4.5 x10@super 11@ cm-3 respectively and the metastables collectively account for ~ 8% of all neutral species. For this power density, excitation of the metastables contribute ~ 44% and ~ 50% of the emission observed at 7774 and 8446 Å respectively, with the O(@super 1@D) metastable being the principal contributor. In the dim mode, the densities of O(@super 1@D) and O(@super 1@S) are three and five orders of magnitude smaller, respectively, than that of ground state atomic oxygen. Throughout the rf power range investigated, the density of O@sub 2@(a @super 1@@delta@@sub g@) is ~ one-third that of O(@super 1@D).