PLASMA IMMERSION ION IMPLANTATION USING AN ELECTRODE WITH EDGE-EFFECT SUPPRESSION BY A DOWNWARDLY CURVING EDGE

摘要

In a plasma reactor, RF bias power is applied from an RF bias power generator to a disk-shaped electrode underlying and insulated from a workpiece and having a circumferential edge underlying a circumferential edge of the workpiece. The RF bias power is sufficient to produce a high RF bias voltage on the workpiece on the order of 0.5-20 kV. Non-uniformity in distribution of plasma across the workpiece is reduced by providing a curvature in a peripheral edge annulus of said electrode whereby the peripheral annulus slopes away from the workpiece support surface. The peripheral edge annulus corresponds to a small fraction of an area of said electrode. The remainder of the electrode encircled by the peripheral annulus has a flat shape.