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:
Sep. 23, 2003
Filed:
Jun. 20, 2001
Yuji Imai, Saitama-ken, JP;
Nikon Corporation, Tokyo, JP;
Abstract
An exposure apparatus and method for a photolithographic process uses a projection optical system that transfers an image of a reticle pattern onto a first shot area on a wafer, the first shot area being made coincident with an image plane within an exposure field of the system. When moving a second shot area into the exposure field, variations in the vertical position of the wafer are compensated by a Z/levelling-stage. Focusing and exposure are performed for the second shot area after an AF sensor system measures and stores a defocus amount of the second shot area relative to the image plane. Repeating this procedure for shot areas on the wafer yields a plurality of defocus amounts, from which any foreign matter existing on the bottom of the wafer is detected. Alternatively, for exposing the first shot area, the vertical position and tilt angle of the wafer are made coincident with those of the image plane. When positioning the second shot area into the exposure field, the tilt angle is kept unchanged, and is measured and stored. Before exposing the second shot area, the vertical position and tilt angle of the wafer is made coincident with those of the image plane. Foreign matter on the wafer is detected from a distribution of the tilt angles on the surface of the wafer.