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Title: Neutral gas temperature measurements of high-power-density fluorocarbon plasmas by fitting swan bands of C{sub 2} molecules

Abstract

The neutral gas temperature of fluorocarbon plasmas in a remote toroidal transformer-coupled source was measured to be greater than 5000 K, under the conditions of a power density greater than 15 W/cm{sup 3} and pressures above 2 torr. The rovibrational bands of C{sub 2} molecules (swan bands, d {sup 3}{pi}{sub g}{yields}a {sup 3}{pi}{sub u}) were fitted to obtain the rotational temperature that was assumed to equal the translational temperature. This rotational-translational temperature equilibrium assumption was supported by the comparison with the rotational temperature of second positive system of added N{sub 2}. For the same gas mixture, the neutral gas temperature is nearly a linear function of plasma power, since the conduction to chamber wall and convection are the major energy-loss processes, and they are both proportional to neutral gas temperature. The dependence of the neutral gas temperature on O{sub 2} flow rate and pressure can be well represented through the power dependence, under the condition of constant current operation. An Arrhenius type of dependence between the etching rate of oxide film and the neutral gas temperature is observed, maybe indicating the importance of the pyrolytic dissociation in the plasma formation process when the temperature is above 5000 K.

Authors:
; ;  [1];  [2];  [2]
  1. Department of Physics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States)
  2. (United States)
Publication Date:
OSTI Identifier:
20787782
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Applied Physics; Journal Volume: 99; Journal Issue: 1; Other Information: DOI: 10.1063/1.2159545; (c) 2006 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; CARBON; CARBON FLUORIDES; CONVECTION; ELECTRON TEMPERATURE; ETCHING; FLOW RATE; ION TEMPERATURE; MIXTURES; MOLECULES; ORGANIC COMPOUNDS; OXIDES; PLASMA; PLASMA DIAGNOSTICS; POWER DENSITY; PRESSURE DEPENDENCE; PRESSURE RANGE PA; PYROLYSIS; TEMPERATURE DEPENDENCE; TEMPERATURE MEASUREMENT; TEMPERATURE RANGE OVER 4000 K

Citation Formats

Bai Bo, Sawin, Herbert H., Cruden, Brett A., Department of Chemical Engineering and Electrical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, and NASA Ames Center for Nanotechnology, Moffett Field, California 94035. Neutral gas temperature measurements of high-power-density fluorocarbon plasmas by fitting swan bands of C{sub 2} molecules. United States: N. p., 2006. Web. doi:10.1063/1.2159545.
Bai Bo, Sawin, Herbert H., Cruden, Brett A., Department of Chemical Engineering and Electrical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, & NASA Ames Center for Nanotechnology, Moffett Field, California 94035. Neutral gas temperature measurements of high-power-density fluorocarbon plasmas by fitting swan bands of C{sub 2} molecules. United States. doi:10.1063/1.2159545.
Bai Bo, Sawin, Herbert H., Cruden, Brett A., Department of Chemical Engineering and Electrical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, and NASA Ames Center for Nanotechnology, Moffett Field, California 94035. Sun . "Neutral gas temperature measurements of high-power-density fluorocarbon plasmas by fitting swan bands of C{sub 2} molecules". United States. doi:10.1063/1.2159545.
@article{osti_20787782,
title = {Neutral gas temperature measurements of high-power-density fluorocarbon plasmas by fitting swan bands of C{sub 2} molecules},
author = {Bai Bo and Sawin, Herbert H. and Cruden, Brett A. and Department of Chemical Engineering and Electrical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 and NASA Ames Center for Nanotechnology, Moffett Field, California 94035},
abstractNote = {The neutral gas temperature of fluorocarbon plasmas in a remote toroidal transformer-coupled source was measured to be greater than 5000 K, under the conditions of a power density greater than 15 W/cm{sup 3} and pressures above 2 torr. The rovibrational bands of C{sub 2} molecules (swan bands, d {sup 3}{pi}{sub g}{yields}a {sup 3}{pi}{sub u}) were fitted to obtain the rotational temperature that was assumed to equal the translational temperature. This rotational-translational temperature equilibrium assumption was supported by the comparison with the rotational temperature of second positive system of added N{sub 2}. For the same gas mixture, the neutral gas temperature is nearly a linear function of plasma power, since the conduction to chamber wall and convection are the major energy-loss processes, and they are both proportional to neutral gas temperature. The dependence of the neutral gas temperature on O{sub 2} flow rate and pressure can be well represented through the power dependence, under the condition of constant current operation. An Arrhenius type of dependence between the etching rate of oxide film and the neutral gas temperature is observed, maybe indicating the importance of the pyrolytic dissociation in the plasma formation process when the temperature is above 5000 K.},
doi = {10.1063/1.2159545},
journal = {Journal of Applied Physics},
number = 1,
volume = 99,
place = {United States},
year = {Sun Jan 01 00:00:00 EST 2006},
month = {Sun Jan 01 00:00:00 EST 2006}
}