Mass spectroscopic investigation of the CH3 radicals in a methane rf discharge

Toyoda, Hirotaka; Kojima, H.; Sugai, Hideo

doi:10.1063/1.101336

Cited by 141 publications

(48 citation statements)

References 12 publications

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“…The CH 4 glow discharges studied here are electropositive. According to previous analyses with QMS, CH 4 + , CH 3 + , C 2 H 5 + , and CH 5 + are the predominant ions in CH 4 glow discharges: 31,47 they are products of electron impact dissociation and ionization processes. In this work, we assumed that CH 5 + was the most abundant ion, so the hypothesis Z =17 ͑Z is the atomic number͒ was considered in our calculations, in contrast to other values proposed in pre- …”

Section: Modelingmentioning

confidence: 99%

Plasma parameters of pulsed-dc discharges in methane used to deposit diamondlike carbon films

Corbella

Rubio‐Roy

Bertrán

et al. 2009

Journal of Applied Physics

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Here we approximate the plasma kinetics responsible for diamondlike carbon ͑DLC͒ depositions that result from pulsed-dc discharges. The DLC films were deposited at room temperature by plasma-enhanced chemical vapor deposition ͑PECVD͒ in a methane ͑CH 4 ͒ atmosphere at 10 Pa. We compared the plasma characteristics of asymmetric bipolar pulsed-dc discharges at 100 kHz to those produced by a radio frequency ͑rf͒ source. The electrical discharges were monitored by a computer-controlled Langmuir probe operating in time-resolved mode. The acquisition system provided the intensity-voltage ͑I-V͒ characteristics with a time resolution of 1 s. This facilitated the discussion of the variation in plasma parameters within a pulse cycle as a function of the pulse waveform and the peak voltage. The electron distribution was clearly divided into high-and low-energy Maxwellian populations of electrons ͑a bi-Maxwellian population͒ at the beginning of the negative voltage region of the pulse. We ascribe this to intense stochastic heating due to the rapid advancing of the sheath edge. The hot population had an electron temperature T e hot of over 10 eV and an initial low density n e hot which decreased to zero. Cold electrons of temperature T e cold ϳ 1 eV represented the majority of each discharge. The density of cold electrons n e cold showed a monotonic increase over time within the negative pulse, peaking at almost 7 ϫ 10 10 cm −3 , corresponding to the cooling of the hot electrons. The plasma potential V p of ϳ30 V underwent a smooth increase during the pulse and fell at the end of the negative region. Different rates of CH 4 conversion were calculated from the DLC deposition rate. These were explained in terms of the specific activation energy E a and the conversion factor x dep associated with the plasma processes. The work deepens our understanding of the advantages of using pulsed power supplies for the PECVD of hard metallic and protective coatings for industrial applications ͑optics, biomedicine, and electronics͒.

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Section: Modelingmentioning

confidence: 99%

Plasma parameters of pulsed-dc discharges in methane used to deposit diamondlike carbon films

Corbella

Rubio‐Roy

Bertrán

et al. 2009

Journal of Applied Physics

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“…Recent data for the upper limit of the sticking coefficients [37] for a number of investigated hydrocarbons and radicals from a low temperature plasma [33,38,39] are compared in Table 2 with assumptions in current re-deposition modeling using MD simulations [40] (Figure 5). …”

Section: Measurement Of Sticking Coefficientsmentioning

confidence: 99%

Status of knowledge of chemical erosion of carbon and critical issues for extrapolation to ITER

Roth

2006

Phys. Scr.

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Abstract:Chemical erosion of-carbon based plasma-facing materials and the re-deposition of tritium containing carbon layers are critical processes for the material choice in ITER. At the occasion of the workshop on Plasma-Surface Interaction related to Fusion (PSIF) the present status of knowledge was defined, suggestions for improved measurements discussed and the importance of atomistic modeling of individual processes underlined. In the present article the status of knowledge for both processes is outlined and important unresolved issues are identified: the extrapolation of measured erosion yields at high particle fluxes towards low energies as expected in detached divertor plasmas and the transport and deposition of hydrocarbon molecules on the divertor plate and walls.Introduction:

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“…͑8͒ and ͑11͔͒ are especially effective in plasma excitation processes because they have large capture cross sections. It is known from mass spectroscopic studies 42,43 that there are a number of excited C m H n species ͑ions and radicals͒ present in the plasma. These species tend to undergo collisional reactions, rather than deexcitation processes which result in OES lines, and could be acting as Penning agents in these nitrogen activation reactions, resulting in the promotion of the N 2 second positive bands.…”

Section: A Oes Analysismentioning

confidence: 99%

Characterization of a-C:H:N deposition from CH4/N2 rf plasmas using optical emission spectroscopy

Clay

Speakman

Amaratunga

et al. 1996

Journal of Applied Physics

147

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Optical emission spectra ͑OES͒ from CH 4 /N 2 rf plasmas, which are used for the deposition of nitrogen-containing hydrogenated amorphous carbon ͑a-C:H:N͒ thin films, have been characterized. Previously unidentified spectral lines have been assigned to atomic N. Further identified species include CH, H, H 2 , N 2 , N 2 ϩ , N, and CN. Variations between spectra from the pure CH 4 or N 2 plasmas and the mixed CH 4 /N 2 plasma are discussed. The enhancement of excited nitrogen species, with the addition CH 4 , is attributed to Penning ionization. The observed OES variations of the CH 4 /N 2 plasma with power, pressure, and CH 4 /N 2 ratio are explained in terms of possible reaction mechanisms and their activation, and correlated with preliminary film growth characteristics.

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Mass spectroscopic investigation of the CH3 radicals in a methane rf discharge

Cited by 141 publications

References 12 publications

Plasma parameters of pulsed-dc discharges in methane used to deposit diamondlike carbon films

Plasma parameters of pulsed-dc discharges in methane used to deposit diamondlike carbon films

Status of knowledge of chemical erosion of carbon and critical issues for extrapolation to ITER

Characterization of a-C:H:N deposition from CH4/N2 rf plasmas using optical emission spectroscopy

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