Position detection apparatus and exposure apparatus

• US 7,103,210 B2
• Filed: 05/18/2005
• Issued: 09/05/2006
• Est. Priority Date: 03/09/1999
• Status: Expired due to Fees

• Current Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Original Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Inventors: Tanaka, Hiroshi
• Primary Examiner(s): CHAWAN, SHEELA C
• Application Number:
  US11/131,428
• Publication Number:
  US 20050220334A1
• Time in Patent Office: 475 Days
• Field of Search: 382/147, 382/151, 382/181, 382/184, 382/190, 382/199, 382/209, 382/216, 382/218, 382/219, 382/266, 382/287, 250/491.1, 250/492.2, 250/492.22, 250/559.36, 349/95, 349/158, 430/5, 430/296, 356/401
• US Class Current: 382/151
• CPC Class Codes: G03F 9/7088 Alignment mark detection, e.g. TTR, TTL, off-axis detection, array detector, video detection
• CPC Class Codes: G03F 9/7092 Signal processing
• CPC Class Codes: G06T 2207/10016 Video; Image sequence
• CPC Class Codes: G06T 2207/30148 Semiconductor; IC; Wafer
• CPC Class Codes: G06T 7/12 Edge-based segmentation
• CPC Class Codes: G06T 7/74 involving reference images or patches

Abstract

A position detection apparatus for detecting a position of a mark on an object includes a camera which captures an image of the mark, an extraction section which extracts a plurality of edge positions of the mark based on a signal derived from the image of the mark, each of the edge positions being associated with a combination of a direction and a polarity of the signal, and a determination section which determines a position of the mark, by comparing each of the plurality of extracted edge positions with a corresponding one of templates prepared for the respective combinations.

Claims

1. An exposure apparatus comprising:

a projection optical system for projecting a pattern onto a substrate;

a chuck on which the substrate is placed; and

a position detection section for detecting a position of a mark on the substrate placed on said chuck,

wherein the substrate is aligned on the basis of a detection result by said position detection section, and then, the substrate is exposed using the pattern,

said position detection section comprising;

an extraction section for observing the mark and extracting a plurality of edge information of the mark in correspondence with attribute information representing features of the edge information, respectively;

a position determination section for comparing each edge information with one of a plurality of templates, which is specified by attribute information corresponding to the edge information and evaluating a plurality of comparison results obtained by comparison to determine the position of the mark; and

a control section for changing at least one of an extraction rule in said extraction section and an evaluation rule in said position determination section on the basis of the plurality of comparison results by said position determination section and causing said extraction section and said position determination section to execute processing again.

2. The apparatus according to claim 1, wherein said extraction section of said position detection section observes the mark with an off-axis scope.

3. The apparatus according to claim 1, wherein said extraction section of said position detection section observes the mark by TTR (Through The Reticle).

4. The apparatus according to claim 1, wherein said extraction section of said position detection section observes the mark by TTL (Through The Lens).

5. The apparatus according to claim 1, wherein each attribute information represents an edge portion of the mark, which is associated with the corresponding edge information.

6. The apparatus according to claim 1, wherein each attribute information represents one of a plurality of extraction conditions under which the corresponding edge information is extracted.

7. The apparatus according to claim 1, wherein said extraction section extracts, as each edge information, information representing an edge position shifted from an actual edge position of the mark by a predetermined distance in one of a plurality of predetermined directions, and each attribute information represents a direction in which an edge position associated with the corresponding edge information is shifted from the actual edge position of the mark by the predetermined distance.

8. The apparatus according to claim 1, wherein said extraction section comprises:

an image sensing section for sensing an image of the mark;

a differential processing section for differentiating the mark image as an image sensing result; and

an edge information generation section for processing the differential result to generate the edge information corresponding to the attribute information.

9. The apparatus according to claim 8, wherein said differential processing section calculates a change rate of an image signal of the mark image along at least two directions of the mark image, and

each attribute information is associated with one of the at least two directions.

10. The apparatus according to claim 9, wherein each attribute information is associated with a sign of the differential result by said differential processing section.

11. The apparatus according to claim 8, wherein each attribute information is associated with a sign of the differential result by said differential processing section.

12. The apparatus according to claim 8, wherein said differential processing section calculates a change rate of an image signal of the mark image across the mark image along row and column directions of the mark image, and

each attribute information is associated with one of the row and column directions and the differential result by said differential processing section.

13. The apparatus according to claim 1, wherein each template includes, as information to be compared with the edge information, position information of a plurality of points defining a corresponding edge.

14. The apparatus according to claim 1, wherein each template includes, as information to be compared with the edge information, position information of points on a continuous line defining a corresponding edge.

15. The apparatus according to claim 1, wherein said extraction section performs noise removal processing for an observation result of the mark and then executes edge information extraction.

16. The apparatus according to claim 1, wherein said extraction section increases a line width associated with the extracted edge information.

17. The apparatus according to claim 1, wherein at least one of the extraction rule and the evaluation rule determined by said control section is stored in a memory and used as a base for processing to be executed later.

18. The apparatus according to claim 1, wherein said extraction section observes the mark under dark field illumination.

19. An exposure apparatus comprising:

a projection optical system for projecting a pattern onto a substrate;

a chuck on which the substrate is placed; and

a position detection section for detecting a position of a mark on the substrate placed on said chuck,

wherein the substrate is aligned on the basis of a detection result by said position detection section, and then, the substrate is exposed using the pattern,

said position detection section comprising;

an extraction section for observing the mark and extracting edge information of the mark;

a position determination section for comparing the edge information with a template and evaluating a comparison result to determine the position of the mark; and

a control section for changing at least one of an extraction rule in said extraction section and an evaluation rule in said position determination section on the basis of the evaluation result by said position determination section and causing said extraction section and said position determination section to execute processing again.