Position detection apparatus and exposure apparatus

• US 6,925,203 B1
• Filed: 03/08/2000
• Issued: 08/02/2005
• Est. Priority Date: 03/09/1999
• Status: Expired due to Term

• Current Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Original Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Inventors: Tanaka, Hiroshi
• Primary Examiner(s): Mehta, Bhavesh M.
• Assistant Examiner(s): CHAWAN, SHEELA C
• Application Number:
  US09/521,210
• Time in Patent Office: 1,973 Days
• Field of Search: 382/151, 382/108, 382/147, 382/155, 382/165, 382/181, 382/184, 382/190, 382/199, 382/201, 382/209, 382/216, 382/218, 382/219, 382/256, 382/260, 382/275, 382/287, 356/399, 356/400, 356/401, 356/508, 356/490, 356/141.4, 356/139, 250/557, 250/492.1, 250/559.36, 250/492.22
• 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. A position detection apparatus for detecting a position of a mark on an object, said apparatus comprising:

a camera which captures an image of the mark;

an extraction section which extracts an edge position in image data obtained by differentiating the image data;

a determination section which determines a position of the mark by comparing the edge position with a template; and

a control section which changes at least one of a parameter used by said extraction section and a parameter used by said determination section, based on a result of the comparing by said determination section.

2. An apparatus according to claim 1, wherein the parameter changed by said control section is stored in a memory and used as a base for processing to be executed later.

3. An apparatus according to claim 1, wherein said determination section performs the comparing by obtaining a degree of matching between the edge position and the template.

4. An apparatus according to claim 3, wherein said determination section determines the position of the mark as a center position of the template of which position is determined based on the degree of matching.

5. An apparatus according to claim 3, wherein the parameter used by said determination section is a threshold for determining the position of the mark with respect to the degree of matching.

6. An apparatus according to claim 1, wherein said determination section performs the comparing using a correlation method.

7. An apparatus according to claim 1, wherein said extraction section differentiates the image data along each of at least two directions.

8. An apparatus according to claim 1, wherein the template includes a plurality of positions of interest.

9. An apparatus according to claim 1, wherein a parameter used for at least one of a noise removal processing for the image data and a correction of the edge position is changed based on a result of the comparing by said determination section.

10. An apparatus according to claim 1, wherein said camera captures the image under a dark field illumination.

11. An apparatus according to claim 1, wherein the parameter used by said extraction section is a threshold for extracting the edge position with respect to a differential value of the image data.

12. A position detection method of detecting a position of a mark on an object, said method comprising steps of:

capturing an image of the mark using a camera;

extracting an edge position in image data obtained in said capturing step by differentiating the image data;

determining a position of the mark by comparing the edge position with a template; and

changing at least one of a parameter used in said extracting step and a parameter used in said determining step, based on a result of the comparing in said determining step.

13. A method according to claim 12, wherein the parameter changed in said changing step is stored in a memory and used as a base for processes to be executed later.

14. A method according to claim 12, wherein, in said determining step, the comparing is performed by obtaining a degree of matching between the edge position and the template.

15. A method according to claim 14, wherein, in said determining step, the position of the mark is determined as a center position of the template of which position is determined based on the degree of matching.

16. A method according to claim 14, wherein the parameter used in said determining step is a threshold for determining the position of the mark with respect to the degree of matching.

17. A method according to claim 12, wherein, in said determining step, the comparing is performed using a correlation method.

18. A method according to claim 12, wherein, in said extracting step, the image data is differentiated along each of at least two directions.

19. A method according to claim 12, wherein the template includes a plurality of positions of interest.

20. A method according to claim 12, wherein a parameter used for at least one of a noise removal processing for the image data and a correction of the edge position is changed based on a result of the comparing in said determining step.

21. A method according to claim 12, wherein, in said capturing step, the camera captures the image under a dark field illumination.

22. A method according to claim 12, wherein the parameter used in said extracting step is a threshold for extracting the edge position with respect to a differential value of the image data.