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. 05, 1986
Filed:
Apr. 26, 1985
Robert D Evans, Bedford, MA (US);
Ward D Halverson, Cambridge, MA (US);
Spire Corporation, Bedford, MA (US);
Abstract
An improved process, optimizing quality and growth rate with independent control of residual stress, is disclosed for the growing of membranes for use as X-ray lithography mask blanks. The process comprises providing a mounting fixture and a low-cost substrate material thereon, cooling the substrate to about the boiling point of hydrogen by passing a liquid coolant in contact with the fixture, depositing by a low-temperature plasma-enhanced method a thin membrane onto the cooled substrate, removing the substrate and the thereon deposited membrane from the fixture, and allowing the substrate thermally to expand by gradually assuming ambient room temperature, whereby the membrane will acquire optimum tensile stress. Preferably, the low-cost substrate is low grade industrial silicon and the membrane is formed of boron nitride, silicon carbide, silicon nitride, amorphous silicon, diamondlike carbon, aluminum oxide, beryllium and silicon oxide.