An electron image projector with automatic alignment

An electron image projector for silicon device processing is described which uses an air-cored solenoid and a caesium iodide photocathode. The alignment method is based on the X-rays which are generated when high-voltage electrons strike matter. Phase sensitive detection is used to convert the off balance to a linear signal which is then fed back into analog electronics. Results are presented showing a marker pattern automatically aligned to an accuracy of 0.1 µm.