Method and apparatus for alignment with a substrate, using coma imparting optics

Patent 5783833 Issued on July 21, 1998. Estimated Expiration Date:

December 12, 2015. Estimated Expiration Date is calculated based on simple USPTO term provisions. It does not account for terminal disclaimers, term adjustments, failure to pay maintenance fees, or other factors which might affect the term of a patent.

Abstract Claims Description Full Text

Patent References

Off axis alignment system for scanning photolithography
Patent #: 5477057
Issued on: 12/19/1995
Inventor: Angeley, et al.

Apparatus for detecting an in-focus position of a substrate surface having a movable light intercepting member and a thickness detector
Patent #: 5483079
Issued on: 01/09/1996
Inventor: Yonezawa

Apparatus for detecting positions of marks in projection aligner wherein an auxiliary pattern is constructed to produce a signal level that is independent of the surface condition of a substrate Patent #: 5483349
Issued on: 01/09/1996
Inventor: Suzuki

Inventors

Assignee

Nikon Corporation

Application

No. 570924 filed on 12/12/1995

US Classes:

250/548, Controlling web, strand, strip, or sheet356/401With registration indicia (e.g., scale)

Examiners

Primary: Westin, Edward P.
Assistant: Giles, Alan L.

Attorney, Agent or Firm

Pennie & Edmonds llp

Foreign Patent References

63-90825 JP. 04/23/1988
2-99907 JP. 04/23/1990
3-42611 JP. 02/23/1991
4-65603 JP. 03/23/1992
4-273246 JP. 09/23/1992
190424 JP. 07/23/1993

International Class

G01N 021/86

Foreign Application Priority Data

1994-12-12 JP

Abstract

A wafer is brought into focus with a projection optical system, and a wafer mark on the wafer is also brought into focus with an off-axis alignment sensor highly accurately according to an automatic focusing process. First, a deviation of the surface of the wafer from an image plane of the projection optical system is measured by an oblique-incidence main AF sensor. For measuring the position of the wafer mark with an imaging device of an alignment system, part of a focusing ray of light from the wafer passes through an optical system, which is not telecentric, composed of an AF relay system and a half beam shield plate, and is detected by the imaging device, whereupon an image of a focusing mark projected onto the wafer is formed on the imaging device. The position of the image of the focusing mark on the imaging device is calibrated on the basis of the deviation which has been measured by the oblique-incidence main AF sensor.