Negative ion densities in Cl{sub 2} and BCl{sub 3} inductively-coupled plasmas
- Sandia National Labs., Albuquerque, NM (United States)
The chlorine negative ion density and the electron density in Cl{sub 2} and BCl{sub 3} inductively-coupled plasmas have been measured in a GEC reference cell operated in the inductively-coupled mode. The chlorine negative ion density was measured as an excess electron density produced by photo-dissociation of the negative ions by 266 nm radiation from a frequency-quadrupled Nd:YAG laser. Both the excess electron density and the steady-state electron density were measured using a microwave interferometer. Various gas mixtures were investigated including pure Cl{sub 2}, pure BCL{sub 3}, and a combination of these gases with each other and with N{sub 2} and Ar. Cl{sup {minus}} densities up to 4 {times} 10{sup 11} cm{sup {minus}3} were measured depending on the gas mixture. The ratio of electron density to Cl{sup {minus}} density was as high as 3 in Cl{sub 2} mixtures, and up to 5 in BCl{sub 3} mixtures. The plasma probed at lower photon energy (355 nm) to photodetach electrons from other negative ions possibly present in the plasma: to within the sensitivity of the measurement (1.3 {times} 10{sup 8} cm{sup {minus}3}), no other negative ions such as BCl{sub x}{sup {minus}} or Cl{sub 2}{sup {minus}} ions were detected. The Cl{sup {minus}} density also changed when BCl{sub 3} was added to Cl{sub 2} discharges. Addition of Ar or N{sub 2} to Cl{sub 2} plasmas had little effect on Cl{sup {minus}} density, but nitrogen addition had very dramatic effects when added to BCl{sub 3}, causing a factor of two increase in the Cl{sup {minus}} density.
- Research Organization:
- Sandia National Laboratory
- Sponsoring Organization:
- USDOE, Washington, DC (United States)
- DOE Contract Number:
- AC04-94AL85000
- OSTI ID:
- 321046
- Report Number(s):
- CONF-970559--
- Country of Publication:
- United States
- Language:
- English
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