| 摘要 |
<p>An electron image projector for transferring mask patterns onto a semiconductor wafer comprises a patterned photoemissive cathode mask (4) and a target (3) formed by the 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 established between the cathode and an electron permeable anode grid (2) situated between the cathode and the target. For fast alignment with low power consumption deflection of the beam is achieved electrostatically. To this end electrostatic deflection plates (16a, 16b), 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 whole of the beam is deflected in the same direction. In another arrangement one 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.</p> |
