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:
Apr. 17, 2012
Filed:
Dec. 27, 2007
Hiroyuki Miyata, Kanagawa, JP;
Takeshi Miyazaki, {dot over (T)}okyo, JP;
Kazuhiko Kobayashi, Tokyo, JP;
Kunito Hayashi, Tokyo, JP;
Hiroyuki Miyata, Kanagawa, JP;
Takeshi Miyazaki, {dot over (T)}okyo, JP;
Kazuhiko Kobayashi, Tokyo, JP;
Kunito Hayashi, Tokyo, JP;
Ricoh Company, Ltd., Tokyo, JP;
Crestec Corporation, Tokyo, JP;
Abstract
A method of evaluating astigmatism of an irradiation system irradiating an electron beam is disclosed. In this method, a figure pattern consisting of plural (for example, four) concentric circles is formed on a reference sample 'WP' and an image (scanned image) is formed based on an electron signal obtained by scanning the electron beam onto the reference sample 'WP'. In the scanned image, the image has a blur in a region with its longitudinal direction parallel to the generating direction of the astigmatism and the size of the blur depends on magnitude of the astigmatism. Therefore, the direction and the magnitude of the astigmatism of the irradiation system of an irradiation apparatus can be detected based on the obtained scanned image.