The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Aug. 08, 1989
Filed:
May. 13, 1988
David S Holbrook, Woburn, MA (US);
Craig R Simpson, Arlington, MA (US);
MRS Technology, Inc., Chelmsford, MA (US);
Abstract
A direct reticle reference alignment system for use in photolithography for use with substrates having optical transmissivity. The system includes a movable stage (14), a transmissive substrate (11) held by the stage and bearing at least one plate mark (15) upon its upper surface, an optical system having a light source (1) for illuminating and projecting a reticle alignment image (4) upon the substrate (11) for alignment with the plate mark (15), a sensor (17) mounted in the stage (14) below the substrate (11) and the plate mark (15) to receive light from the projected alignment image (4), the sensor (17) producing an electrical signal related to the degree of alignment, and a stage control actuated by the signal to position the stage (14) and, so, align the substrate (11) with the reticle (4). The sensor (17) includes a light channel (19), such as a fiber optic rod, positioned to receive images from the lower surface (13) of said substrate ( 11) and carry them to the photocell. The detector may include a quadcell and a corresponding light channel for each cell in the quadcell.