Effects of Plasma and Evaporated Atoms on the Spatial Distribution of Coating Film Thickness for Electron Beam-Induced Material Evaporation

Abstract

This paper investigates the spatial distributions of electron beam-evaporated atoms and electron beam-induced plasma in the coating process. The materials evaporated by electron beams first form vapour and then a little of plasma is generated in the vapour. The spatial distributions of electron beam-induced atoms and plasma play an important role on the coating uniformity of composition and thickness. The radial distribution of coating deposition thickness of electron beam-evaporated atoms predicted by this study agrees with the available experimental data. The predicted distribution of ion density in the electron beam-induced plasma agrees with the available measured data. The results reveal that the normalized coating thicknesses at the divergence angle of 6 and 14 degrees of vapor source, respectively, are 0.8 and 0.2 of these at divergence angle of 0 degree of vapor source for titanium and aluminum evaporated separately. The similar tendency for the decreasing coating thickness with the radial distance is also obtained for the co-evaporation of aluminum, titanium, and copper. High rotation rate of substrate of vapor source leads to the small deposition rate. Most ions in the electron beam-induced plasma are attracted by electrons of the electon beam and are located at the neighbourhood of the beam region. Therefore, the ion and ion-attracted electron densities rapidly decrease with the increasing radial distance from the electron beam.