Electron lithography using a photocathode
OwnerGeorge R. Brandes, Philip M. Platzmaninventors
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Abstract
Sub-micron pattern delineation, importantly in the fabrication of large scale integrated devices, is based on a patterned photocathode. Functionally, the photocathode plays the role of the mask in competing systems, either in proximity printing or in projection. In operation, the photocathode is illuminated by ultraviolet radiation to release electrons which are brought to focus on a resist-coated wafer with assistance of a uniform magnetic field together with an accelerating applied voltage.
Claims16
Method for device fabrication entailing pattern delineation of minimum feature size smaller than 0.25 .mu.m, such delineation comprising irradiating a resist with patterned electron radiation,
- characterized in that such patterned radiation is yielded from a UV excited photocathode comprising free surface noble metal photoemissive material, in which said free surface is the surface of a photoemissive layer of a thickness of at least 100 .ANG., in that said radiation is focused on such resist as spaced an integral number of cyclotron resonance periods from the photocathode, and in which focusing and electron acceleration result from applied magnetic and electric fields.
Method for device fabrication entailing at least one projection electron imaging step by projection from a photocathode, characterized in that a project image is changed in size relative to the image on the photocathode, in that electrons in transit are subjected to a magnetic field which, as measured in the direction orthogonal to transiting electrons, spatially changes in cross-section area at least once, and in that change in image size accompanies change in cross-section area of the field.
Dependencies are inferred from the claim text.