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:
Feb. 20, 1990
Filed:
Oct. 21, 1988
Karel D Van Der Mast, Pijnacker, NL;
U.S. Philips Corporation, New York, NY (US);
Abstract
An electron image projector for transferring mask patterns onto a semiconductor wafer comprises a patterned photo-emissive cathode mask (1) and a target (3) such as a semiconductor wafer (11) coated with an electron sensitive resist (10). Accelerated by a uniform electric field E and focussed by a uniform magnetic field H a patterned electron beam is projected from the cathode onto the target with unity magnification. The electric field E is at least mainly established between the cathode and the target A foil is provided for protecting the photocathode against poisoning by gas liberated from the target upon electron beam bombardement. To avoid adversely influencing the imaging electron beams the foil may be constituted as a metal foil with a thickness of about 0,1 .mu.m for 25 kV electrons.