Pressure and electron temperature dependence of H− density in a hydrogen plasma

Abstract

The density of negative ions in a low-pressure hydrogen plasma has been investigated as a function of neutral gas pressure, plasma density, and electron temperature. The comparison of the experimental data, obtained by the photodetachment technique, with theoretical results derived from computed reaction rates, seems to indicate that hydrogen negative-ion production occurs mainly through the process of electron attachment on vibrationally excited hydrogen molecules.

Hydrogen Plasma Characteristics for Photoresist Stripping Process in a Cylindrical Inductively Coupled Plasma

“…The explanations for the cause of these instability regions reported in the literature are related to negative ions in plasma [16]. H 2 gas chemistry leads to the formation of negative ions in H 2 plasma, primarily because of the dissociative electron attachment to vibrationally excited molecules [17][18][19]. The mechanism for the formation of H-negative ions in H 2 plasma and the rates of dissociative attachment in H 2 are strongly dependent on the electronic excitation involving super-excited states (SES) in the ionization continuum, as shown by Eq.…”

Forty-five years with cesiated surface plasma sources

“…Until recently, the emission current densities of H-ions which can be obtained from plasma sources under optimum conditions greatly exceeded the rated current densities calculated with allowance for the known reaction rates for creation and destruction of negative ions in a plasma. New data for the cross sections for production of H-ions in the interaction of electrons with vibrationally excited hydrogen molecules, which were given in Bacals's review article, [44] would make it possible to reconcile the calculated production rates of H-ions with those observed experimentally. However, even under optimum conditions, the maximum current density of H-ions from plasma sources (j <0.1 A/cm 2 ) is an order of magnitude smaller than that obtained from a discharge in a planotron.…”

Development of a 14 GHz Microwave H− Source

“…This field arrangement enables the source to produce multiply charged ions because microwave power accelerates electrons to higher kinetic energy in an enhanced electron confinement field [4]. These high energy electrons in a H 2 plasma efficiently produce vibrationally excited molecules (H * 2v ), which are the parent molecules for H − in electron volume process [5]. In this process, formed H * 2v dissociate to pairs of an atomic hydrogen and a H − by capturing low energy electrons.…”