The role of photon self-absorption on the H (n 
               = 2) density determination by means of VUV emission spectroscopy and TDLAS in low pressure plasmas

Merk, F.; Friedl, R.; Briefi, S.; Fröhler-Bachus, C.; Fantz, U.

doi:10.1088/1361-6595/abc93d

Cited by 5 publications

(5 citation statements)

References 23 publications

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“…In all cases, the majority of the VUV photons were measured in the Lyman band, followed by the Ly-α line and Werner bands. The increase in molecular to atomic emission ratio with increasing pressure potentially indicates an increase in self-absorption of the Ly-α line at higher pressures which is consistent with the literature [17]. Further analysis of this trend would require a measurement of the atomic to molecular hydrogen density ratio for varying pressures and an estimation of the plasma density profile [17], which is beyond the scope of the present work.…”

Section: Local Fluxsupporting

confidence: 82%

“…The increase in molecular to atomic emission ratio with increasing pressure potentially indicates an increase in self-absorption of the Ly-α line at higher pressures which is consistent with the literature [17]. Further analysis of this trend would require a measurement of the atomic to molecular hydrogen density ratio for varying pressures and an estimation of the plasma density profile [17], which is beyond the scope of the present work. With increasing power, there was negligible change in the relative contributions of each of the spectral features.…”

Section: Local Fluxsupporting

confidence: 82%

“…The primary of these is self-absorption along the optical path by neutral atomic and molecular hydrogen. A reasonable estimation of the Ly-α escape factor would require knowledge of the emission profile of the plasma and the neutral and atomic molecular hydrogen densities [17], which is out of the scope of this work.…”

Section: Estimation Of the Total Radiancementioning

confidence: 99%

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Absolute measurement of vacuum ultraviolet fluxes from inductively coupled plasmas via metal surface photoemission currents

Richmond,

Machacek,

Davoodianidalik

et al. 2024

Meas. Sci. Technol.

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Quantifying vacuum-ultraviolet (VUV) fluxes typically requires vacuum compatible spectrometers and is often associated with significant cost and effort. A simple technique for the absolute measurement of local VUV fluxes from plasmas using the photoemission from a set of coated metal plates, is described. The radiant power from a 13.56 MHz hydrogen plasma operating at 40-100 mTorr and with an RF input power from 100 to 120 W was investigated by irradiating a set of 2cm diameter Au, Ag and Cu plates. The variation in photoemission currents was compared with the photoelectric yield curves to estimate the absolute flux incident on the surfaces in the 113-190 nm range. The measured fluxes were found to have an uncertainty of 5 – 30% when compared with the VUV spectrometer measurements. The VUV output power was found to have a maximum at a pressure of 70-80 mTorr and to increase with RF power. In all cases, the VUV output power was measured to be approximately 12 - 16% of the RF input power to the matching network, in good agreement with spectroscopy results.

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Section: Local Fluxsupporting

confidence: 82%

Section: Local Fluxsupporting

confidence: 82%

See 1 more Smart Citation

Absolute measurement of vacuum ultraviolet fluxes from inductively coupled plasmas via metal surface photoemission currents

Richmond,

Machacek,

Davoodianidalik

et al. 2024

Meas. Sci. Technol.

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“…PlanICE is a planar inductively coupled plasma experiment [17]. The cylindrical stainless steel vessel has 15 cm in diameter and 10 cm in height.…”

Section: Laboratory Experiments Planicementioning

confidence: 99%

A portable diagnostic system for the quantification of VUV fluxes emitted from low-temperature plasmas

Friedl¹,

Fröhler-Bachus²,

Fantz³

2023

Meas. Sci. Technol.

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Vacuum-Ultraviolet (VUV) spectroscopy is linked to a huge effort, in particular if absolute numbers are required. To overcome this, a flexible device is developed based on a photodiode and optical filters for wavelength selection. Characterization of the diagnostic is performed against a VUV spectrometer that is radiometrically calibrated down to 46 nm. In the first instance, the latter is used for an analysis of VUV spectra of inductively coupled low-temperature plasmas for a variety of discharge gases and mixtures. The measured photon fluxes can easily have comparable magnitude as the occurring ion flux, and it is demonstrated that the photonic energy distribution can change drastically with varying external parameters (pressure, RF power). This highlights the need for energy resolution for VUV flux detection and a set of ten optical filters was selected for the VUV diode system according to the respective prominent emission ranges of typical discharge gases for plasma processing. Recommended filter combinations for each of the discharge gases and mixtures are given. The developed diagnostic is calibrated in-house against the VUV spectrometer, which makes energy-resolved absolute VUV flux measurements up to photon energies of 27 eV possible. The calibration is performed individually for all the investigated discharge gases and the corresponding filter combinations, and an accuracy of better than 25 % compared to the VUV spectrometer is attested for the investigated parameter space (0.3-10 Pa, 200-1100 W RF power). Its applicability is demonstrated by measuring VUV fluxes at two further low-temperature plasma setups.

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“…It means that its ashing rate increases with pressure and ICP power. The VUV fluence, however, owing to self-absorption by H 2 , is larger at lower pressure, where the ion flux is also higher and the atomic flux is proportionally lower. Considering our intent of modifying both the PS and the PDMSB, a slower etch rate of the topcoat is rather beneficial, although the larger ion flux reduces the selectivity with PS (severely ion-limited etch rate).…”

Section: Resultsmentioning

confidence: 99%

Dry-Etching Processes for High-Aspect-Ratio Features with Sub-10 nm Resolution High-χ Block Copolymers

Pound-Lana

Bézard

Petit-Etienne

et al. 2021

ACS Appl. Mater. Interfaces

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Directed self-assembly of block copolymers (BCP) is a very attractive technique for the realization of functional nanostructures at high resolution. In this work, we developed full dry-etching strategies for BCP nanolithography using an 18-nm pitch lamellar silicon-containing block copolymer. Both an oxidizing Ar/O2 plasma and a non-oxidizing H2/N2 plasma are used to remove the topcoat material of our BCP stack and reveal the perpendicular lamellae. Under Ar/O2 plasma, an interfacial layer stops the etch process at the top-coat/BCP interface, which provides an etch-stop but also requires an additional CF4-based breakthrough plasma for further etching. This interfacial layer is not present in H2/N2. Increasing the H2/N2 ratio leads to more profound modifications of the silicon-containing lamellas, for which a chemistry in He/N2/O2 rather than Ar/O2 plasma produces a smoother and more regular lithographic mask. Finally, these features are successfully transferred into silicon, silicon-on-insulator and silicon nitride substrates. This work highlights the performance of a silicon-containing block-copolymer at 18 nm pitch to pattern relevant hardmask materials for various applications, including microelectronics.

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The role of photon self-absorption on the H (n = 2) density determination by means of VUV emission spectroscopy and TDLAS in low pressure plasmas

Abstract: The role of photon self-absorption on the H (n= 2) density determination by means of VUV emission spectroscopy and TDLAS in low pressure plasmasTo cite this article before publication: Frederik Merk et al 2020 Plasma Sources Sci.

Cited by 5 publications

References 23 publications

Absolute measurement of vacuum ultraviolet fluxes from inductively coupled plasmas via metal surface photoemission currents

Absolute measurement of vacuum ultraviolet fluxes from inductively coupled plasmas via metal surface photoemission currents

A portable diagnostic system for the quantification of VUV fluxes emitted from low-temperature plasmas

Dry-Etching Processes for High-Aspect-Ratio Features with Sub-10 nm Resolution High-χ Block Copolymers

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