Treating workpieces with beams

Abstract

In apparatus for controlling the treatment of a workpiece by a beam emanating from a source, there is translational relative movement in two orthogonal directions between the beam and the workpiece support element, and control of velocity in one (control) direction occurs in response to a detector, mounted behind the support, which periodically samples the beam through a moving slot in the support element. This slot extends over the range of movement in the control direction. An ion implanter is shown in which the support element is a constantly spinning disk the axis of which is translated in the control direction. Another ion implanter is shown in which the support element is a moving belt. A simple control circuit, useful for both embodiments, achieves a uniform ion dosage upon semiconductor substrates at a high production rate despite variations in beam intensity. The detector is not affected by a shower of electrons upon the support that neutralizes charge on the workpieces.

Dependencies are inferred from the claim text.