Secondary electron emission from magnetron targets

Abstract

Ion-induced secondary electron emission of surfaces occurs in all gas
discharges which have contact to surfaces such as electrodes or chamber walls. These
secondary electrons (SE) play an important role, for instance, in the performance of
DC discharges, RF discharges and magnetron sputtering discharges. SE generation can
be separated into potential electron emission due to the neutralization of the incident
ion upon impact and kinetic electron emission due to the electronic stopping of the
penetrating ion in the solid. SE due to neutralization is usually described by Auger
processes and the density of states of the electrons in the solid, whereas kinetic electron
emission scales with the electronic stopping of the ion in the solid, as being calculated
by ion collision simulations. The measurement of the energy distribution of the SEs of
three metals (Al, Ti, Cu) and their oxides reveals the occurrence of Auger peaks, which
are not reflected by standard models such as the Hagstrum model. Instead, in this
paper, a model is proposed describing these Auger peaks by Auger neutralization of
holes created by the collision cascade of the incident ion. This shows decent agreement.
The contribution of Auger peaks in the metals Al and Ti is very significant, whereas
it is negligible in the case of Cu. The implication of these energy distributions to the
performance of magnetron sputtering discharges is discussed.

Ammonia synthesis by plasma catalysis in an atmospheric RF helium plasma

“…In contrast, the N 2 (C) lines are a bit less intense when using this surface. SEs injected into the plasma-after acceleration in the plasma sheath-contribute to the high-energy tail of the EEDF [66]. They should enhance the excitation of species with larger excitation thresholds such as N + 2 (B) (threshold 20 eV).…”