Factors determining energy values of ion beams for ion-beam deposition

IBD (ion-beam deposition) is performed with a very low-energy ion beam, who se energy value is not simply determined. For the accurate evaluation an ex cess energy due to the source-plasma potential should be added to the energ y value obtained simply from the source-bias voltage. However, the plasma p otential is changing dependently on the secondary electrons From chamber wa ll as well as the plasma parameters. We studied theoretically how the plasm a potential is affected by the chamber material as well as by the plasma pa rameters. Then, we measured floating potentials of several materials immers ed in a microwave plasma for studying the influence of secondary electrons from the wall. The result suggests that the potential of a plasma surrounde d by material of a high secondary-electron coefficient becomes low and cons equently the excess energy decreases. (C) 1999 Elsevier Science B.V. All ri ghts reserved.