Two dimensional optical mask positioning W.R.T. semiconducting layer - uses position marker optical imaging position control system which has coordinates represented by signals

摘要

The system for positioning a workpiece in two dimensions is esp. applicable to aligning an optical mask in x and y coordinates w.r.t. a selected position of a semiconducting layer. They are more simply and economically realised than in conventional arrangements and enable positioning in a series of repeatable addressed points with an accuracy of less than one tenth of a micrometer. Search time between points is reduced by using more direct paths between them. The workpiece is fixed at a processing point movable in the plane in which it is to be positioned in two orthogonal axes. The processing station has corresp. coordinate position markings which are partially projected with magnification onto a stationary scanning point and converted into a signal corresp. to the coordinates. A position error signal is derived for the position control system.