Energy Spectrum of an Abnormal Glow Discharge Created Electron Beam

Abstract

Abnormal glow discharge created electron beams, applied to microelectronic film processing, have been studied theoretically and experimentally. The beam mode of operation occurs in the discharge region adjacent to the glow to arc transition regime. A numerical model simulates the energy distribution I(E) of transmitted beam electrons both inside and outside the cathode sheath. Changes in the I(E) spectrum are calculated as a function of distance in the field-free region outside the sheath. In the theoretical model of beam generation and propagation we include secondary electrons created at the cathode following ion bombardment, the electron energy gain that occurs in the field of the cathode sheath, elastic electron-atom collisions, electron-atom ionization collisions, electron-atom excitation collisions, super-elastic electron-atom collisions, and electron-electron collisions. The calculated I(E) spectrum agrees with experimentally measured data at a total ambient pressure of 0.2-0.9 torr in a helium-oxygen mixture with a cathode current density in the range of 10-100 mA/cm2.