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. 24, 2007
Filed:
May. 11, 2006
Euclid E. Moon, Boston, MA (US);
Euclid E. Moon, Boston, MA (US);
Massachusetts Institute of Technology, Cambridge, MA (US);
Abstract
An apparatus and method measures the gap between one substantially planar object, such as a mask, and a second planar object, such as a substrate. A gapping mark is used for measuring a gap between the first and second plates. The gapping mark includes a first grating on a first surface of a first plate, the first grating having a first uniform period in a first direction. A second grating is located on the first surface of the first plate, the second grating being adjacent to the first grating in the first direction, the second grating having a second uniform period in the first direction. The gapping mark also includes a third grating on the first surface of the first plate, the third grating being adjacent to the first grating in a second direction, the second direction being substantially orthogonal to the first direction, the third grating having the second uniform period in the first direction. A fourth grating is located on the first surface of the first plate, the fourth grating being adjacent to the third grating in the first direction.