Effect of surface derived hydrocarbon impurities on Ar plasma properties

Abstract

The authors report on Langmuir probe measurements that show that hydrocarbon surfaces in contact with Ar plasma cause changes of electron energy distribution functions due to the flux of hydrogen and carbon atoms released by the surfaces. The authors compare the impact on plasma properties of hydrocarbon species gasified from an etching hydrocarbon surface with injection of gaseous hydrocarbons into Ar plasma. They find that both kinds of hydrocarbon injections decrease electron density and slightly increase electron temperatures of low pressure Ar plasma. For low percentages of impurities ($1% impurity in Ar plasma explored here), surface-derived hydrocarbon species and gas phase injected hydrocarbon molecules cause similar changes of plasma properties for the same number of hydrocarbon molecules injected into Ar with a decrease in electron density of $4%.

Energy conversion efficiency in low- and atmospheric-pressure plasma polymerization processes with hydrocarbons

“…and with the efficiency of power coupling, ηe, whereby hydrocarbon plasmas show lower ne than Ar due to higher energy losses in inelastic collisions. 34 Note that similar ne values are typically reported for homogeneous DBDs in Ar (10 10 to 10 11 cm -3 ). 35,36 For the well-defined vertical flow in the LP plasma reactor at sufficiently high total gas flow rate, Fm > 10 sccm, the proportionality factor in eq.…”

“…For Epl = Ea, it thus follows that the maximum ECE reaches 37% of the maximum conversion, c0 (≤ 1), in non-thermal plasmabased monomer conversion. At AP in homogeneous DBD Ar plasma, ne may be comparable to LP, 10 10 to 10 11 cm -3 , 35,36 while Te is lower, around 0.5 eV compared to around 2.5 eV at 10 Pa. 30,34,67,68 The drop in Te, however, is accompanied by enhanced density of Ar metastable states (Ar 1s), underlining the importance of energy transfer through Ar*. 68 A small addition of molecular gas to Ar, however, results in a noticeable drop in ne.…”

Comparative analyses of plasma probe diagnostics techniques

“…EEPFs measured with 37 in ICP filled with ArþCH 4 at the condition of strong polymer film deposition. 44 The deviation from Maxwellian EEPFs is clearly seen at e > e* ¼ 11.56 eV.…”

“…Such data can be used with full confidence for plasma density, electron temperature, and reaction rate calculations as appropriated integrals of EEDF. 43 The EEPFs measured in the same reactor operating with Ar and CH 4 added to plasma from surface and gaseous sources 44 are shown in Fig. 14.…”

Plasma polymerization of hexamethyldisiloxane: Revisited

“…This behavior was observed, for example, for Ar plasma with CH 4 admixture, resulting in a decrease of n e and a slight increase in T e . [ 117 ] Pure HMDSO or HMDSO‐dominated plasma was found to show a decrease both in n e and T e as compared with pure Ar plasma at comparable conditions, indicating a large energy transfer into dissociation. [ 94,118,119 ] A 20% drop in T e was reported already for highly diluted HMDSO/Ar plasma, which saturated at about 30% lower T e values for higher HMDSO concentrations (RF CCP, 6 Pa).…”