Optical alignment of masks for X-ray lithography
AssigneeSperry Corporation
InventorJames B. Thaxter
Life of this patent
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Abstract
Optical alignment of the relative positions of cooperating masks and substrates is achieved for use in the generation by x-radiation of complex and compact patterns. Small fiduciary marks are actually illuminated by coherent visible light and the resultant diffraction patterns are used for alignment purposes. Fresnel half-period zone plates are used to produce interference patterns in the form of an operator-observable information bearing pattern on a viewable screen.
Claims9
Apparatus for aligning a first planar optically transparent element with respect to a second planar optically transparent element disposed in substantially parallel relation comprising:
- first and second thin films affixed to major adjacent surfaces of said first and second planar elements respectively,
- said films being provided with first and second apertures respectively, each of said apertures containing a Fresnel zone plate,
- means for illuminating said Fresnel zone plate with collimated light, and
- means for viewing an interference pattern formed by light passing through said Fresnel zone plates.
Dependencies are inferred from the claim text.