IMAGING AND ALIGNMENT TESTS ON AN ELECTRON PROJECTION SYSTEM

Improvements to an Electron Projection System are described which eliminate many of the reported disadvantages of this type of system. The performance of a field-compensating electrostatic chuck that remedies pattern distortion caused by the wafer (anode) is described in conjunction with imaging and alignment tests on 75-mm-diam wafers. Proximity effects and reimpacting backscattered electron flooding are shown to be minimized by reduction of the electron exposure energy thereby eliminating the need for pattern compensation in the mask. Line and space patterns with 0. 5- mu m dimensions were exposed and resolved without compensation for exposure dosage of larger patterns. Overlay registration results are given for two-layer alignment tests using e-beam-fabricated masks to expose 75-mm-diam wafers.