H atom surface loss kinetics in pulsed inductively coupled plasmas

Abstract

Pulsed plasmas are very powerful tools to investigate mechanisms. This paper is focused on H atom kinetics in low-pressure high-density inductively coupled pulsed plasmas. We explore pure H 2 , H 2 /N 2 , CH 4 /H 2 and CH 4 /N 2 mixtures. These gas mixtures offer two very different kinds of wall conditions, which are stainless-steel and hydrocarbon-coated walls. It shows that H loss probability (β) is sensitive to wall conditions. Efforts are made to understand β evolutions with the different parameters. The effect of pressure in non-depositing plasmas is also investigated. Evolution of H atom surface loss probability is linked to ion flux measurements. Ion bombardment promotes H surface loss.

Numerical study of the influence of surface reaction probabilities on reactive species in an rf atmospheric pressure plasma containing humidity

“…In both cases, the surface reaction rates depend on the surface coverage of reactants and the fluxes of species incident onto the surface. As a result, reaction probabilities are strongly dependent on experimental conditions, such as pressure and gas mixture [27][28][29], wall material [25,26,28,[30][31][32][33][34], temperature [35][36][37], and surface roughness [36,37]. Ion bombardment can have a significant effect on the value of γ [27,38] through the generation of free surface sites and desorption of adsorbates.…”

“…As a result, reaction probabilities are strongly dependent on experimental conditions, such as pressure and gas mixture [27][28][29], wall material [25,26,28,[30][31][32][33][34], temperature [35][36][37], and surface roughness [36,37]. Ion bombardment can have a significant effect on the value of γ [27,38] through the generation of free surface sites and desorption of adsorbates. If reactive gases are used in the system, plasma products can deposit on the chamber walls, and change γ over time [39], leading to drifts in the properties of the plasma [40].…”

Diagnostics of low-pressure hydrogen discharge created in a 13.56 MHz RF plasma reactor

“…Let us note that this thematic of atomic loss (or atomic reflection) on the surface is not only limited to fusion-related studies, but concerns most of the low-pressure plasma processes. The measurement of the reflection coefficient and its dependence with experimental parameters is a recurrent issue in many plasma applications, ranging from microelectronics to fusion, as evidenced by the high number of papers dealing with this subject over decades (Wood and Wise 1962, Cartry et al 2000, Rousseau et al 2001, Lopaev and Smirnov 2004, Macko et al 2004, Kurunczi et al 2005, Bousquet et al 2007, Guerra 2007, Mozetic and Cvelbar 2007, Rutigliano and Cacciatore 2011, Jacq et al 2013, Samuell and Corr 2014, Sode et al 2014, Marinov et al 2014a. Finally, hydrogen plasma characterization is of interest not only because of the atomic surface loss issue, but because hydrogen gas is often used for plasma processing such as hydrogenation (Hatano and Watanabe 2002), the treatment of Si wafers for creating subsurface defects in layers (Ghica et al 2010), chemical vapor deposition of diamonds (Hassouni et al 1996), functional materials or polycrystallization of amorphous Si, and the creation of positive Fonash 1993, Cielaszyk et al 1995) or negative ions in ionsources (Iordanova et al 2011, Kalache et al 2004, Ahmad et al 2013.…”

Surface loss probability of atomic hydrogen for different electrode cover materials investigated in H2-Ar low-pressure plasmas

“…At the wall H atoms recombine forming H 2 . Other loss processes such as three-body recombination in the plasma volume or pumping can be neglected for the present conditions [14][15][16][17]34 . The wall loss time t wH , which is the inverse of the wall loss rate coefficient, is the mean time for a hydrogen atom to reach the plasma surrounding wall.…”