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. 25, 1981
Filed:
Nov. 26, 1979
Applicant:
Inventors:
Assignees:
Hitachi, Ltd., Tokyo, JP;
Nippon Telegraph & Telephone Public Corporation, Tokyo, JP;
Attorney:
Primary Examiner:
Int. Cl.
CPC ...
G01N / ;
U.S. Cl.
CPC ...
250307 ; 250310 ; 2504 / ;
Abstract
This invention relates to a method of detecting a mark by an electron beam, the mark being provided on a sample, which includes the steps of scanning the electron beam over an area of the mark in such a manner that the electron beam is subjected to chopping by sampling pulses having a higher frequency than the scanning frequency, eliminating a component of noise from a detected signal representative of the mark, synchronously rectifying the detected mark signal, binary-coding the detected mark signal as compared with a suitable threshold value, and detecting a position of the mark by using the binary-coded signal.