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:
Mar. 03, 1992
Filed:
Nov. 08, 1990
Applicant:
Inventors:
Johannes A de Poorter, Eindhoven, NL;
Johannes F Verhoeven, Eindhoven, NL;
Assignee:
U.S. Philips Corporation, New York, NY (US);
Attorney:
Primary Examiner:
Assistant Examiner:
Int. Cl.
CPC ...
H01J / ;
U.S. Cl.
CPC ...
250397 ; 250398 ; 250311 ;
Abstract
A degree of contamination can be measured in a charged particle beam system by means of a contamination monitor which is provided with a carrier having an aperture for transmitting a charged particle beam and a membrane which is connected to the carrier and which covers the aperture. The thickness of a contamination layer deposited on the membrane can be determined by measurement of a decrease of the transmission of the membrane as the contamination increases. The accuracy of measurement is enhanced by selecting a central portion of the particle beam transmitted by the membrane.