Collisional deactivation of two-photon-excited Ar (4p; J = 0, 2) states by<b>H<sub>2</sub>and several hydrocarbon and fluorine containing molecules</b>

Francis, A.; Czarnetzki, Uwe; Döbele, H. F.; Sadeghi, N.

doi:10.1051/epjap:1998266

Cited by 10 publications

(9 citation statements)

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“…The observed levels were chosen, such that population due to excitation out of metastable levels is generally low. Furthermore, quenching in the pressure range, where the experiment was operated (65 Pa), and quenching particularly with molecular gases (O 2 ) is very effective [16][17][18]. Therefore, even in metastable levels the population density is so low, that excitation out of metastables can be neglected.…”

Section: Electron Dynamicsmentioning

confidence: 99%

Space and phase resolved plasma parameters in an industrial dual-frequency capacitively coupled radio-frequency discharge

Schulze

Gans

O’Connell

et al. 2007

J. Phys. D: Appl. Phys.

125

128

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The dynamics of high energetic electrons (11.7 eV) in a modified industrial confined dual-frequency capacitively coupled RF discharge (Exelan, Lam Research Inc.), operated at 1.937 MHz and 27.118 MHz, is investigated by means of phase resolved optical emission spectroscopy. Operating in a He-O 2 plasma with small rare gas admixtures the emission is measured, with one-dimensional spatial resolution along the discharge axis. Both the low and high frequency RF cycle are resolved. The diagnostic is based on time dependent measurements of the population densities of specifically chosen excited rare gas states. A time dependent model, based on rate equations, describes the dynamics of the population densities of these levels. Based on this model and the comparison of the excitation of various rare gas states, with different excitation thresholds, time and space resolved electron temperature, propagation velocity and qualitative electron density as well as electron energy distribution functions are determined. This information leads to a better understanding of the dual-frequency sheath dynamics and shows, that separate control of ion energy and electron density is limited.

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Section: Electron Dynamicsmentioning

confidence: 99%

Space and phase resolved plasma parameters in an industrial dual-frequency capacitively coupled radio-frequency discharge

Schulze

Gans

O’Connell

et al. 2007

J. Phys. D: Appl. Phys.

125

128

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“…Quenching of this Ar transition by SF 6 is significantly stronger; the measured rate amounts to 7.7ϫ10 Ϫ10 s Ϫ1 /cm Ϫ3 . 18 For an SF 6 mole fraction of 50% at 600 mTorr and 450 K, this corresponds to a quenching rate of 5.4ϫ10 6 s Ϫ1 . The radiative rate of the Ar emission at 750 nm is 48ϫ10 6 s Ϫ1 , so even ignoring the quenching affect of the oxygen, collisional deactivation has a measureable affect on the observed emission at the higher pressures.…”

Section: A Variation With Pressurementioning

confidence: 99%

Emission, thermocouple, and electrical measurements in SF6/Ar/O2 SiC etching discharges

Brown

Scofield

Ganguly

2003

Journal of Applied Physics

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In SiC etching plasma devices, we have recorded plasma emission from Ar, F, and O atoms in SF6/Ar/O2 rf discharges as a function of pressure, input power, and mixture fraction. At fixed power, the emission intensities rise nearly linearly with increasing pressure between 100 and 300 mTorr; with pressure increases to 600 mTorr, the emission intensity rolls off due to the increase in collisional de-excitation. At fixed pressure, Ar and O atom emission shows a similar functional dependence on input power with a roll off at the higher powers due to decreasing reduced electric field strength (E/n, where n denotes the number density). In contrast, the F atom emission increase with increasing power is nearly linear. This reflects the fact that F atoms are produced by dissociative attachment of SF6 (for lower E/n conditions) in addition to direct electron impact dissociation. Electrical measurements, with a variable interelectrode gap discharge, indicate that the electric field to pressure (E/p) ratio does drop with increasing input power. Thermocouple measurements show that the ground electrode temperature increases with increasing power. The dissociative attachment of SF6 increases with increasing temperature as well. The SiC etch rate increases nearly linearly with input power up until the polymer buildup becomes the rate limiting process. At fixed pressure, the Ar emission from the 750 nm line decreases with increasing additions (up to 10%) of O2. This is due to resonantly enhanced quenching of the 4p (13.5 eV) manifold by oxygen atoms. In marked contrast, the F atom emission intensity increases suggesting F atom production by neutral species chemistry. Over the pressure (100–600 mTorr) and power (20–60 W) range studied, the Ar 750 nm emission line serves as a good actinometer for the 704 nm F line provided that there is not a high degree (or changing degree) of O2 dissociation. Resonant deactivation of the 750 nm line through collisional interaction with O atoms, can make the 750 nm line problematic. Under such conditions our previous work indicates that the Ar 641 nm line can provide an alternative actinometer. The excited state of the 641 nm transition lies above the O atom ionization limit making it immune from resonant quenching.

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“…σ v i,N2/H2 is the quenching coefficient of excited states by N 2 or H 2 . The quenching coefficient for the argon upper state, 2p 1 , by H 2 is taken from [13] to be 2.7 × 10 −11 cm 3 s −1 . The quenching of this state by N 2 is equal to 3.2 × 10 −11 cm 3 s −1 [14].…”

Section: Production and Loss Of Excited Statesmentioning

confidence: 99%

Validity of actinometry to measure N and H atom concentration in N₂-H₂direct current glow discharges

Thomaz

Amorim

Souza

1999

J. Phys. D: Appl. Phys.

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Abstract. The validity of actinometry to measure N and H atoms in nitrogen-hydrogen direct current (dc) glow discharges was investigated. The experiments were conducted in positive columns of dc glow discharges, in mixtures of N 2 -xH 2 , where x varies from zero to one, pressures between 133.33 and 533.32 Pa and discharge currents from 1 to 50 mA. The electric fields were measured by electric probes (17 V cm −1 < E < 32 V cm −1 ), and the gas temperatures (490 K < T g < 910 K) were deduced from the rotational transitions of molecular-band systems. The actinometry was performed using argon as the actinometer gas and compared with laser induced fluorescence measurements of ground-state atoms, in order to establish the limits of the validity of actinometry. A theoretical approach was used in order to interpret the behaviour of the emission lines. In nitrogen-hydrogen positive columns, the actinometry method indicated the correct behaviour of the N atoms density in the range of zero to one for x and for H atoms in the region from x = 0 to x = 0.2.

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Collisional deactivation of two-photon-excited Ar (4p; J = 0, 2) states byH₂and several hydrocarbon and fluorine containing molecules

Cited by 10 publications

References 0 publications

Space and phase resolved plasma parameters in an industrial dual-frequency capacitively coupled radio-frequency discharge

Space and phase resolved plasma parameters in an industrial dual-frequency capacitively coupled radio-frequency discharge

Emission, thermocouple, and electrical measurements in SF6/Ar/O2 SiC etching discharges

Validity of actinometry to measure N and H atom concentration in N₂-H₂direct current glow discharges

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Collisional deactivation of two-photon-excited Ar (4p; J = 0, 2) states byH2and several hydrocarbon and fluorine containing molecules

Cited by 10 publications

References 0 publications

Space and phase resolved plasma parameters in an industrial dual-frequency capacitively coupled radio-frequency discharge

Space and phase resolved plasma parameters in an industrial dual-frequency capacitively coupled radio-frequency discharge

Emission, thermocouple, and electrical measurements in SF6/Ar/O2 SiC etching discharges

Validity of actinometry to measure N and H atom concentration in N2-H2direct current glow discharges

Contact Info

Product

Resources

About

Collisional deactivation of two-photon-excited Ar (4p; J = 0, 2) states byH₂and several hydrocarbon and fluorine containing molecules

Validity of actinometry to measure N and H atom concentration in N₂-H₂direct current glow discharges