Ion composition of beam plasma formed by electron beam evaporation of YSZ ceramic in medium vacuum

Abstract

Plasma with high content of rare-earth elements finds applications in ion implantation and surface modification technologies. Here, we have studied the mass-to-charge ion composition of multicomponent beam plasma formed by irradiation of a refractory dielectric target of zirconia ceramic partially stabilized with yttria (YSZ) by a continuous focused electron beam with energy 3–11 keV in a gas atmosphere (helium, or a mixture of helium and argon or oxygen) in the forevacuum pressure range (about 4–6 Pa). Using a quadrupole mass analyzer, we find that, at a power sufficient for intense evaporation of the target, the ion mass spectrum, in a background of residual atmosphere and operating gas ions, contains peaks of singly charged positive ions of yttrium, zirconium, and their oxides and dioxides with amplitudes comparable to those of the residual atmosphere and the operating gas, which indirectly indicates the presence of a high proportion of target material ions in the plasma. We find that signals of oxides of zirconium and yttrium ions decrease while signals of dioxides of these elements increase as the separation (along the electron beam direction) between the analyzer and the target increases. With intensive e-beam evaporation, the fraction of ions of target components surpasses the fractions of ions of all other gaseous plasma components.