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. 07, 1990
Filed:
Jul. 26, 1988
Tatiana E Jewell, Bridgewater, NJ (US);
Donald L White, Springfield, NJ (US);
AT&T Bell Laboratories, Murray Hill, NJ (US);
Abstract
A lithography system is disclosed which is capable of doubling the spatial frequency resolution associated with conventional systems. A spatial filter, positioned to intercept the Fraunhofer diffraction pattern of the mask being exposed, is configured to prevent certain orders of the diffraction pattern (in most causes the O-order and .+-.2nd, 3rd, . . . orders) from reaching the wafer's surface. The remaining orders reaching the wafer surface (in most cases the .+-. first-order beams) will produce a cos-type interference pattern with a period half of that if the mask grating were imaged without spatial filtering. Therefore, for a system with a given magnification factor m, a mask grating with a period p will be exposed on the wafer surface as a grating with a period of p'=pm/2. Advantageously, the spatial filtering technique of the present invention allows for a variety of different structures (conventional gratings, chirped and phase-shifted gratings, grids, Fresnel zone plates, etc.), as well as structures of different sizes and orientations, to be included on one mask and transferred to the wafer with a single exposure cycle.