A
plasma reactor for
processing a
semiconductor wafer includes a side wall and an overhead ceiling defining a chamber, a workpiece support
cathode within the chamber having a working surface facing the ceiling for supporting a
semiconductor workpiece, process gas inlets for introducing a process gas into the chamber and an RF bias power generator having a bias
power frequency. There is a bias power
feed point at the working surface and an RF conductor is connected between the RF bias power generator and the bias power
feed point at the working surface. A
dielectric sleeve surrounds a portion of the RF conductor, the sleeve having an
axial length along the RF conductor, a
dielectric constant and an axial location along the RF conductor, the length,
dielectric constant and location of the sleeve being such that the sleeve provides a
reactance that enhances
plasma ion density uniformity over the working surface. In accordance with a further aspect, the reactor can include an annular RF
coupling ring having an inner
diameter corresponding generally to a periphery of the workpiece, the RF
coupling ring extending a sufficient portion of a distance between the working surface and the overhead
electrode to enhance
plasma ion density near a periphery of the workpiece.