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. 09, 2003
Filed:
Oct. 11, 2001
Devices and methods for compensating for tilting of a leveling table in a microlithography apparatus
Toshio Ueta, Foster City, CA (US);
Nikon Corporation, Tokyo, JP;
Abstract
With respect to exposure apparatus, apparatus and methods are disclosed for compensating for lateral shift of a leveling table caused by a tilt (&thgr;) of the leveling table. One embodiment includes a wafer-stage-position loop servo, a leveling-table tilt-position loop servo, and a first feed-forward loop from the leveling-table tilt-position loop servo to the wafer-stage-position loop servo. The first feed-forward loop converts a torque-control signal for the leveling table to a linear-acceleration-control signal for the wafer stage. Thus, the wafer stage moves laterally to compensate for lateral shift of the leveling table. If the exposure apparatus includes a reticle stage controlled by a reticle-stage-position loop servo, then the subject apparatus can include (in addition to or in place of the first feed-forward loop) a second feed-forward loop from the leveling-table tilt-position loop servo to the reticle-stage-position loop servo. The second feed-forward loop converts a positional signal for the leveling table to a position-control signal for the reticle stage, to cause the reticle stage to undergo lateral compensatory motion. The methods and apparatus provide a faster and more accurate compensation for lateral shifts of the leveling table.