Determination of Ar metastable atom densities in Ar and Ar/H₂inductively coupled low-temperature plasmas

Abstract

Ar metastable atoms are important energy carriers and surface interacting species in low-temperature plasmas that are difficult to quantify. Ar metastable atom densities (N Ar,m) in inductively coupled Ar and Ar/H 2 plasmas were obtained using a model combining electrical probe measurements of electron density (N e) and temperature (T e), with analysis of spectrally resolved Ar plasma optical emission based on 3p → 1s optical emission ratios of the 419.8 nm line to the 420.1 nm line. We present the variation of N Ar,m as the Ar pressure and the addition of H 2 to Ar are changed comparatively to recent adsorption spectroscopy measurements.

Isotope effects on plasma species of Ar/H2/D2 plasmas

“…With increasing molecular gas flow, the N e decreases, while increasing pressure causes an increase. Using an optical technique reported previously, 12 we found that densities of Ar metastable atoms are very similar with H 2 and D 2 addition to Ar plasmas. At 30 mTorr, N e decreased by a factor of almost 10 ($2.5 Â 10 11 cm À3 !…”

“…The electron behavior changes significantly with the addition of H 2 or D 2 and increases in pressure. 11,12 Ar metastable atom densities are governed by generation (Ar atom densities, N e , and T eff ) and quenching (molecule-metastable atom collisions, wallmetastable atom collisions, and electron-metastable atom collisions). The reduction in N e is more pronounced as pressure increases due to an increase in inelastic electron-molecule collisions.…”

“…4 Recent works have aimed at characterizing plasma properties and surface interacting species in Ar/H 2 plasmas. [4][5][6][7][8][9][10][11][12] At low pressure (1-100 mTorr), major surface interacting species in Ar/H 2 plasmas are ions, reactive H atoms, UV/VUV photons, and Ar metastable atoms. Gudmundsson first measured the ion mass and energy distributions for most ion types present (H þ , H 2 þ , H 3 þ , and Ar þ ).…”

“…Gudmundsson first measured the ion mass and energy distributions for most ion types present (H þ , H 2 þ , H 3 þ , and Ar þ ). 9,10 Wang et al 11 and Fox-Lyon et al 12 recently reported on the effect of H 2 addition to Ar plasma on Ar metastable atom concentrations using optical methods and probe measurements (by collection of electron energy information and optical emission of excited Ar 3p ! They found that plasma density decreased rapidly with the introduction of H 2 into the pure Ar plasma.…”

A Computationally Assisted Ar I Emission Line Ratio Technique to Infer Electron Energy Distribution and Determine Other Plasma Parameters in Pulsed Low-Temperature Plasma

“…Passive optical diagnostics that are non-invasive and non-perturbative, like the 420.1/419.8 nm argon-emission line-height-ratio technique [2][3][4], are desirable because they can be implemented in real time and can be used to determine metastable-atom density [2,5] and effective electron temperature [4]. Emission spectra have been shown to correlate with high energy electrons [2,3,6,7].…”