Energy-transfer processes in neon-hydrogen mixtures excited by electron beams

Abstract

Energy- and charge-transfer processes in neon-hydrogen mixtures (500-1400 hPa neon and 0.001-3 hPa hydrogen partial pressures) excited by a pulsed low-energy (approximately 10 keV) electron beam were investigated using time-resolved spectroscopy. Time spectra of the hydrogen Lyman-alpha line, neon excimer emission (second continuum), and neon atomic lines (3p-3s transitions) were recorded. The time-integrated intensity of the Lyman-alpha emission was measured for the same range of gas mixtures. It is shown that direct energy transfer from Ne*2 excimers and neon atoms in the four lowest excited states as well as recombination of H3+ ions are the main channels populating atomic hydrogen in the n=2 state. A rate constant of (4.2+/-1.4)x10(-11) cm3 s(-1) was obtained for the charge transfer from Ne2+ ions to molecular hydrogen. A lower limit for the depopulation rate constant of Ne*2 excimers by molecular hydrogen (combination of energy transfer and ionization) was found to be 1.0 x 10(-10) cm3 s(-1).

Enhanced performance of an EUV light source (λ = 84 nm) using short-pulse excitation of a windowless dielectric barrier discharge in neon

“…Timescales for commercial implementation of litho-toolsets based on EUV sources/optics at λ = 13.6 nm (currently the preferred wavelength for next generation lithography) remain uncertain due to ongoing technological challenges [17]. Issues relating to the efficient production of Ne * 2 species are also of interest for the parallel development of high pressure Ne/H 2 plasma lamps generating relatively narrow linewidth VUV emission at 121.6 nm (H Lyman α) [18,19]. In this paper we investigate the electrical and optical characteristics of a DBD with a neon gas fill, and, for the first time as far as we are aware, undertake a detailed comparison of Ne DBD lamp performance for both pulsed and sinusoidal voltage excitation waveforms under otherwise identical operating conditions.…”

“…The electrical and optical measurements are used to evaluate the relative efficiency for EUV production for both excitation methods. The underlying particle kinetics responsible for the production of Ne * 2 excimers in medium pressure (0.1-1.0 bar) neon plasmas have been studied by several groups using various excitation techniques; including e-beam pumping [18,[20][21][22], RF excited DBDs (13.56 MHz) [23] and dc/pulsed glows [24,25]; and are now reasonably well understood. A partial energy level diagram for atomic and molecular neon is shown in figure 1.…”

“…where k 3 = 1 × 10 5 s −1 (τ 3 ∼ 10 µs) [18]. Similarly, the Ne * 3 P 1 atomic state undergoes three-body conversion to form the Ne * 2 0 + u ( 3 P 1 ) (high v) excimer (see figure 1) which rapidly decays radiatively (τ ∼ 2 ns) [27] from high-lying vibrational states giving rise to the weaker first continuum band centred on λ = 76 nm.…”

Electron beam induced light emission

“…Also different emission characteristics such as narrow atomic line radiation or specific molecular bands can be observed. A process which has been studied in detail is energy transfer from Ne to H 2 leading to selective and narrow-band emission of the Lyman-α line at 121.6 nm in atomic hydrogen [8,9]. Another light source uses a mixture of argon and water vapour radiating on a molecular band of OH * around 310 nm [10].…”

Photoionisierungs‐Massenspektrometrie mit neuer Lichtquelle

“…Die Energietransfermechanismen führen dann zu optischen Übergängen in der Beimengung und damit zur Lichtemission bei den für die Beimengung charakteristischen Wellenlängen. Für SPI ist insbesondere der Energietransfer von Neon auf Wasserstoff interessant, der selektiv zur Emission der Lyman‐a‐Atomlinie des Wasserstoffs bei 121 nm (10, 25 eV) führt 13)…”