| 摘要 |
A screen lens array system including a lens cover plate or top plate and a screen lens array or bottom plate for use in a parallel charged particle beam exposure system is disclosed. The screen lens array, which comprises a pair of lens plates mutually aligned with respect to one another, breaks up a flood beam of charged particles into a multiplicity of beams in parallel and focuses them onto a substrate target surface. The charged particle flood beam impinges the smaller apertures, of the upper lens plate, which serve as apertures to control image aberrations. The larger set of apertures, of the lower lens plate, are influenced by the electric field between the screen lens array and the target surface to form the embodiment of most of the lens action. Mounted above and displaced from the screen lens array is the lens cover plate which also contains an array of apertures. By imparting a linear, mechanical motion to the top plate, it selectively controls, i.e., masks, the passage of the flood beam through certain, but not all, of the apertures of the bottom plate and, therefore, onto the target surface.
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