The etching of CHF3 plasma polymer in fluorine-containing discharges

Bariya, Anand J.; Shan, Houchao; Frank, Curtis W.; Self, S. A.; McVittie, J.P.

doi:10.1116/1.585784

Cited by 18 publications

(7 citation statements)

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“…Chemical reactions that occur at the reactor wall are subsequently not treated in the model, even though they are known to be important. [3][4][5][6][7][8][9]11,12 In this model, only ion neutralization reactions are simulated at the reactor wall. Inputs to the model include the species of interest, the thermodynamic properties of the species, and the kinetic reaction mechanisms and values describing the formation and de-struction of the species.…”

Section: Model Resultsmentioning

confidence: 99%

“…Many researchers have observed that the growth rate and composition of films grown in fluorocarbon plasmas directly correlate with the concentrations of low molecular weight fluorocarbon radicals (CF x , xр3) that are present near a substrate or reactor wall. [3][4][5][6] It is often concluded that the CF x species are direct precursors to film formation, although the details of the heterogeneous nucleation chemistry remain unclear. Alternatively, Fisher and co-workers 7 have shown that the radicals near surfaces in the plasma chamber may be byproducts of dissociative surface reactions or sputtering rather than being precursors to film growth.…”

Section: Introductionmentioning

confidence: 99%

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Macromolecule formation in low density CF4 plasmas: The influence of H2

Schabel

Peterson

Muscat

2003

Journal of Applied Physics

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High molecular weight fluorocarbon species are regarded as important contributors to the nucleation of films and particulates in fluorocarbon plasmas. The chemical reaction mechanisms by which fluorocarbon macromolecules form within a plasma are generally unknown. To elucidate these mechanisms, experiments were conducted in a rf capacitively coupled discharge in a Gaseous Electronics Conference reference cell. The relationships between macromolecule growth and plasma pressure, power, flow rate, and the fraction of H 2 in the CF 4 gas feed are identified. Macromolecule growth was found to increase with increased pressure and rf power, and decreased flow rate. A set of electron-induced dissociation and radical-recombination reactions are simulated using Chemkin-Aurora, a commercially available plasma chemistry model, and are in good agreement with the experimental results of macromolecule growth. We show that a primary mechanism by which fluorocarbon macromolecules form in a plasma occurs by electron-induced dissociation of a fluoroalkane to produce a fluoroalkyl radical and a fluorine atom, followed by a three-body radical-radical recombination reaction with CF 3 . Hydrogen is shown to have a profound effect on this reaction sequence by reducing the gas phase atomic fluorine concentration through the formation of HF which in turn increases the CF 3 concentration available to participate in the macromolecule growth process. At moderate levels of hydrogen in the feed gas (Ͻ20%), macromolecule growth is directly correlated with the fraction of hydrogen in the feed gas. At high concentrations of hydrogen, hydrofluorocarbon and hydrocarbon growth occurs in the plasma at the expense of fluorocarbon macromolecule growth. The conditions under which the formation of these species occurs is consistent with observations in the literature of dramatic reductions in silicon dioxide etching rate. The transition between the formation of fluorocarbon macromolecules and hydrocarbon species in a CF 4 /H 2 plasma is shown to be fundamental to understanding the growth process of each class of species within the plasma.

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Section: Model Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Macromolecule formation in low density CF4 plasmas: The influence of H2

Schabel

Peterson

Muscat

2003

Journal of Applied Physics

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“…Besides their role in the gas phase and surface chemistry of molecular radicals and ions, these F atoms are well known to etch silicon containing surfaces [41,42] and hydrocarbon polymer surfaces [43,44]. The physical modifications induced on the PP surfaces after plasma treatment can be investigated by AFM.…”

Section: Afm Imagingmentioning

confidence: 99%

Increasing the Hydrophobicity of a PP Film Using a Helium/CF4 DBD Treatment at Atmospheric Pressure

Geyter

Morent

Gengembre

et al. 2008

Plasma Chem Plasma Process

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Plasma surface modification is widely used to tailor the surface properties of polymeric materials. Most treatments are performed using low pressure plasma systems, but recently, atmospheric dielectric barrier discharges (DBDs) have appeared as interesting alternatives. Therefore, in this paper, an atmospheric He + CF 4 DBD is used to increase the hydrophobicity of a polypropylene (PP) film. The surface characterization of the PP film is performed using contact angle measurements, X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM). Results show that the hydrophobic properties of the polymer films are greatly enhanced after plasma treatment as evidenced by an increased contact angle. The incorporation of fluorine on the surface is significant (45 at%), demonstrating the ability of the used DBD set-up to generate fluorine-containing functional groups on the PP surface.

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“…10 Previous work 11 on the plasma deposition of films from CHF 3 indicated that the deposition rate with CHF 3 was much higher than with pure fluorocarbons like CF 4 , C 2 F 6 , and C 3 F 8 . This was attributed to the higher precursor concentration and the lower free fluorine generation 12 in CHF 3 plasmas relative to the plasmas of fluorocarbons. X-ray photoelectron spectroscopy ͑XPS͒ analyses showed that films deposited from CHF 3 were more highly crosslinked than those from C 3 F 8 , and thus were expected to have higher thermal stability.…”

Section: Introductionmentioning

confidence: 99%

Plasma chemistry in fluorocarbon film deposition from pentafluoroethane/argon mixtures

Agraharam

Hess

Kohl

et al. 1999

Journal of Vacuum Science &Amp; Technology A: Vacuum, Surfaces, and Films

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Plasma-enhanced deposition of fluorocarbon films was performed at 120°C from a mixture of pentafluoroethane (CF 3 CHF 2) and argon in a parallel plate plasma reactor. Mass spectrometry of the reactor effluent was used to gain an understanding of the plasma chemistry of this monomer. The monomer primarily dissociated into CF 3 • and CHF 2 • in the plasma. The results from mass spectrometry indicated that CHF 2 * was the primary precursor for deposition and that the fluorine radicals in the plasma were primarily scavenged as CF 4 and HF. Monomer conversion ͑fraction of monomer fragmented͒ in the plasma was determined based on mass spectrometer partial pressure analysis of CH 3 CHF ϩ fragments ͑parent molecule: CF 3 CHF 2 ͒ before and after plasma ignition. The conversion correlated directly with both the applied power and the deposition rate. The overall gas phase reactions did not change significantly with rf power within our range of operation, indicating a common reaction mechanism at all powers. No significant change in the composition of the deposited films was found, as measured by x-ray photoelectron spectroscopy ͑XPS͒, supporting the common mechanism conclusion. Further, XPS studies showed a fluorine-to-carbon ratio between 1.05 and 1.15 suggesting extensive crosslinking of the polymer. Infrared spectra of the deposited films showed negligible CH x concentration despite the presence of hydrogen in the monomer.

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The etching of CHF3 plasma polymer in fluorine-containing discharges

Cited by 18 publications

References 0 publications

Macromolecule formation in low density CF4 plasmas: The influence of H2

Macromolecule formation in low density CF4 plasmas: The influence of H2

Increasing the Hydrophobicity of a PP Film Using a Helium/CF4 DBD Treatment at Atmospheric Pressure

Plasma chemistry in fluorocarbon film deposition from pentafluoroethane/argon mixtures

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