Impact of gas heating in inductively coupled plasmas

Hash, David; Bose, Deepak; Rao, M. V. V. S.; Cruden, Brett A.; Meyyappan, M.; Sharma, Surendra P.

doi:10.1063/1.1390503

Cited by 53 publications

(32 citation statements)

References 60 publications

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“…In particular, gas temperature, the basic thermodynamic state parameter, decides the neutral gas density with state equation and helps us understand the power consumption. 20,21 Gas temperature is always estimated using radiative transitions of diatomic molecules, such as N 2 , C 2 , OH, CO, whose rotational temperature was considered to be equal to gas translational temperature. [22][23][24][25][26] It is worthwhile to note that the ratio of vibrational temperature to rotational temperature can suggest nonequilibrium level of microplasma.…”

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confidence: 99%

Heat transport of nitrogen in helium atmospheric pressure microplasma

Zhong

2013

Applied Physics Letters

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Stable DC atmospheric pressure normal glow discharges in ambient air were produced between the water surface and the metallic capillary coupled with influx of helium gas. Multiple independent repeated trials indicated that vibrational temperature of nitrogen rises from 3200 to 4622 K, and rotational temperature of nitrogen decreases from 1270 to 570 K as gas flux increasing from 20 to 80 sccm and discharge current decreasing from 11 to 3 mA. Furthermore, it was found that the vibrational degree of the nitrogen molecule has priority to gain energy than the rotational degree of nitrogen molecule in nonequilibrium helium microplasma.Comment: 4 pages, 5 figures, accepted by AP

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confidence: 99%

Heat transport of nitrogen in helium atmospheric pressure microplasma

Zhong

2013

Applied Physics Letters

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“…Though this work is limited to only dc discharges; similar conclusions are expected for rf, inductive, and microwave reactors. Indeed, both experimental diagnostics − and modeling ,− of gas and substrate heating in inductive and electron cyclotron resonance plasmas used in semiconductor processing have been reported. All of this suggests that a deliberate cooling of the substrate needs to be introduced if room temperature or low-temperature growth is desired for a given set of conditions, including a reasonable power.…”

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confidence: 99%

The Significance of Plasma Heating in Carbon Nanotube and Nanofiber Growth

et al. 2004

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The effect of the plasma on heating the growth substrate in plasma enhanced chemical vapor deposition (PECVD) of carbon nanotubes is characterized for the first time. This effect, which is commonly ignored in the nanotube/nanofiber literature, is the sole heating mechanism in this work for catalyst pretreatment and growth of straight and vertically aligned multiwalled carbon nanofibers. Significant temperatures, as high as 700 °C, are induced from a C2H2:NH3 direct current (dc) plasma with no other heat source present. To model the behavior of the plasma-heated substrate platform, we have developed a 1-D dc discharge model that incorporates a cathode platform energy balance, including ion bombardment, thermal radiation, and solid and gas conduction. The predicted gas-phase species present are correlated with the morphology of nanofibers grown by exclusive plasma heating as well as by heating from plasma in combination with a conventional resistive heater. The understanding of plasma heating and its accurate modeling are essential for reactor design for wafer scale production of vertically aligned nanofibers.

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“…26 In our previous work 19 n n was obtained using an approximate gas heating rate assumed based on publications on neutral heating in inductively coupled plasmas. [27][28][29] In this work, the neutral density n n is determined based on the ideal gas law for neutrals ͑P n = n n k B T trans ͒, with T trans obtained based on the neutral gas temperature determined from OES ͑Sec. II B͒ and P n measured experimentally using a fast response pressure gauge.…”

Section: Evaluation Of Electron Temperature Using Millimeter Wave Intmentioning

confidence: 99%

Laser-rf creation and diagnostics of seeded atmospheric pressure air and nitrogen plasmas

Luo

Denning

Scharer

2008

Journal of Applied Physics

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A laser initiation and radio frequency ͑rf͒ sustainment technique has been developed and improved from our previous work to create and sustain large-volume, high-pressure air and nitrogen plasmas. This technique utilizes a laser-initiated, 15 mTorr partial pressure tetrakis ͑dimethylamino͒ ethylene seed plasma with a 75 Torr background gas pressure to achieve high-pressure air/nitrogen plasma breakdown and reduce the rf power requirement needed to sustain the plasma. Upon the laser plasma initiation, the chamber pressure is raised to 760 Torr in 0.5 s through a pulsed gas valve, and the end of the chamber is subsequently opened to the ambient air. The atmospheric-pressure plasma is then maintained with the 13.56 MHz rf power. Using this technique, large-volume ͑1000 cm 3 ͒, high electron density ͑on the order of 10 11-12 cm −3 ͒, 760 Torr air and nitrogen plasmas have been created while rf power reflection is minimized during the entire plasma pulse utilizing a dynamic matching method. This plasma can project far away from the antenna region ͑30 cm͒, and the rf power budget is 5 W / cm 3. Temporal evolution of the plasma electron density and total electron-neutral collision frequency during the pulsed plasma is diagnosed using millimeter wave interferometry. Optical emission spectroscopy ͑OES͒ aided by SPECAIR, a special OES simulation program for air-constituent plasmas, is used to analyze the radiating species and thermodynamic characteristics of the plasma. Rotational and vibrational temperatures of 4400-4600Ϯ 100 K are obtained from the emission spectra from the N 2 ͑2+͒ and N 2 + ͑1−͒ transitions by matching the experimental spectrum results with the SPECAIR simulation results. Based on the relation between the electron collision frequency and the neutral density, utilizing millimeter wave interferometry, the electron temperature of the 760 Torr nitrogen plasma is found to be 8700Ϯ 100 K ͑0.75Ϯ 0.1 eV͒. Therefore, the plasma deviates significantly from local thermal equilibrium.

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Impact of gas heating in inductively coupled plasmas

Cited by 53 publications

References 60 publications

Heat transport of nitrogen in helium atmospheric pressure microplasma

Heat transport of nitrogen in helium atmospheric pressure microplasma

The Significance of Plasma Heating in Carbon Nanotube and Nanofiber Growth

Laser-rf creation and diagnostics of seeded atmospheric pressure air and nitrogen plasmas

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