SHEATH DYNAMICS IN PLASMA IMMERSION ION-IMPLANTATION

Time-resolved Langmuir probe measurements of the sheath dynamics and i on flux measurements in static and dynamic modes have been made. In th e case of supersonic moving sheaths the experimental data qualitativel y shows that the presheath is suppressed. The results of the sheath me asurements are compared to a modified model description for the non-st ationary sheath during plasma immersion implantation, which includes t he suppression of the presheath at supersonic velocity of the plasma b oundary. Analytical formulas are given for planar, cylindrical and sph erical geometry. Reasonable agreement is obtained for spherical geomet ry according to a dome-like boundary around a small, flat substrate.