Electron image projector.

摘要

An electron image projector for transferring mask patterns onto a semiconductor wafer comprises a patterned photo-emissive chathode mask (4) and a target (3) such as a semiconductor wafer (11) coated with an electron sensitive resist (10). Accelerated by a uniform electric field E and focussed by a uniform magnetic field H a patterned electron beam is projected from the cathode onto the target with unity magnification. The electric field E is at least mainly established between the cathode and the target and protecting the photocathode against poisoning with gas liberated from the target by electron beam bombardement without adversely influencing the imaging electron beam the foil may be constituted as a metal foil with a thickness of about 0,1 mu m for 25 kV electrons.