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. 15, 2003
Filed:
Dec. 22, 2000
Jan Martijn Krans, Eindhoven, NL;
Peter Christiaan Tiemeijer, Eindhoven, NL;
FEI Company, Hillsboro, OR (US);
Abstract
Multi-beam lithography apparatus is used for writing patterns on a substrate such as a wafer for ICs. The patterns may have details of various dimensions. In order to enhance the production rate, it is attractive to write fine details with a small spot and large details with a large spot. It is known to vary the spot size by varying the emissive surface of the electron source. In accordance with the invention the spot size is varied by varying the size of the beam limiting aperture , thus enabling optimization of the beam current in dependence on the spot size. A preferred embodiment is provided with an additional (condenser) lens such that the object distance remains constant when the magnification of the lens system is varied.