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:
Jul. 10, 2001
Filed:
Jul. 27, 1999
Juan R. Maldonado, Menlo Park, CA (US);
Etec Systems, Inc., Hayward, CA (US);
Abstract
An optical mask for high resolution optical lithography using short wavelength light, e.g., 157 nm, uses membranes of a material that is transparent to the desired wavelength. The thin membranes are held under tensile stress by a supporting structure, such as a silicon wafer. Because the membranes are thin, the heating of the membrane material during generation of the overlying lithographic patterns is reduced. This is particularly advantageous when a material such as calcium fluoride is used as the transparent medium of the mask because calcium fluoride has a high thermal expansion coefficient. Thus, the membrane will suffer little distortion during the production of the mask. The lithographic pattern is produced using a thin layer of a absorptive material, such as palladium. Because both the absorptive material and the membrane are thin, there is little back scattering during the generation of the lithographic pattern by e-beam writing, and consequently, no proximity correction is necessary.