| 摘要 |
An electron image projector for transferring mask patterns onto a semiconductor wafer comprises a patterned photoemissive cathode mask and a target formed by the semiconductor wafer coated with an electron sensitive resist. A patterned electron beam is projected from the cathode onto the target with unity magnification by acceleration with a uniform electric field E and focussing by a uniform magnetic field H. The electric field E is established between the cathode and an electron permeable anode grid situated between the cathode and the target. For fast alignment with low power consumption, beam deflection is achieved electrostatically. The electrostatic deflection plates which may be integral with the anode grid or form part of a further grid, are arranged for deflecting at least part of the beam as it travels from the anode grid to the target. In one arrangement to correct for misalignment, the entire beam is deflected in the same direction. In another arrangement part of the beam is oscillated in one direction, while another part of the beam is simultaneously oscillated at a different frequency in a different direction, and phase sensitive detection is used to align the mask and the target.
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