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:
Oct. 27, 1998
Filed:
Aug. 07, 1996
W Ralph Knowles, North Andover, MA (US);
Philips Electronics North America Corporation, New York, NY (US);
Abstract
An environmental scanning electron microscope with, field emission gun providing for a spatial resolution of the specimen under examination of 2nm which is comparable to the spatial resolution of high vacuum field emission scanning electron microscopes even though the specimen is contained in the gaseous environmental of the specimen chamber. The objective lens assembly of this environmental scanning electron microscope includes a differentially pumped aperture system having at least four differentially pumped vacuum zones to provide a pressure difference of up to approximately 10.sup.10 Torr between the field emission gun and the specimen. The differentially pumped aperture system further includes at least four pressure limiting apertures defining the differentially pumped vacuum zones through which the electron beam passes. One of the pressure limiting apertures is formed of a pressure limiting aperture assembly which includes a plurality of stacked annular apertures. Further, an electron detection assembly is provided for detecting signals emanating from the surface of the specimen. The electron detection assembly includes a printed circuit board having a signal ring electrode biased to collect secondary electrons emanating from the surface of the specimen and a final pressure limiting aperture integrally formed therewith which extends through the signal ring electrode so that the electron beam path through the gaseous environment of the specimen chamber is minimized.