Alignment apparatus
AssigneeCanon Kabushiki Kaisha
InventorsMitsugu Yamamura, Minoru Yomoda
Life of this patent
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Abstract
An alignment apparatus for positioning on a wafer an image of a mask formed by a projection optical system. The apparatus includes a first detecting system for detecting the distance between an imaging plane of the optical system and the wafer, a driving mechanism for moving the wafer in the direction of the optical axis of the optical system and a second detecting system for detecting the amount of movement of the wafer. The driving mechanism is controlled while the distance detected by the first detecting system is compared with the amount of movement detected by the second detecting system, whereby the wafer is correctly and accurately positioned on the imaging plane of the optical system.
Claims16
An apparatus for aligning an object with an imaging plane of an optical system, comprising:
- a first detecting means for detecting the position of the object with respect to the imaging plane of the optical system;
- displacement means for changing the positional relation of the object relative to the imaging plane of the optical system;
- a second detecting means for detecting the amount of change in the positional relation of the object relative to the imaging plane of the optical system by said displacement means;
- and
- control means for controlling said displacement means on the basis of the results of detection by said first and second detecting means, said control means comparing sequentially the results of detection by said first and second detecting means with each other and controlling said displacement means so that the results of detection by said first and second detecting means co-ordinate with each other.
An alignment apparatus comprising:
- an electrostrictive element;
- detecting means for detecting the amount of change in said electrostrictive element;
- and
- control means for controlling charging/discharging of said electrostrictive element on the basis of the difference between the amount of change detected by said detecting means and a predetermined set amount.
An apparatus for aligning a flat object with an imaging plane of an optical system, comprising:
- a plurality of first detecting means, each of said first detecting means detecting the position of the object with respect to the imaging plane of the optical system;
- a plurality of displacement means, each of said displacement means changing the positional relation of an associated portion of the object relative to the imaging plane of the optical system;
- a plurality of second detecting means, each of said second detecting means detecting the amount of change in the positional relation between an associated portion of the object relative to the imaging plane of the optical system by an associated one of said displacement means, independently from the change by the remaining displacement means;
- and
- control means for controlling each of said plural displacement means individually on the basis of the result of detection by an associated one of pairs of said first and second detecting means.
Dependencies are inferred from the claim text.