Article of manufacture bearing a universal alignment target

• US 6,671,049 B1
• Filed: 10/30/2000
• Issued: 12/30/2003
• Est. Priority Date: 10/29/1999
• Status: Expired due to Term

• Current Assignee: Cognex Corporation
• Original Assignee: Cognex Corporation
• Inventors: Silver, William
• Primary Examiner(s): FULLER, RODNEY EVAN
• Application Number:
  US09/699,540
• Time in Patent Office: 1,156 Days
• Field of Search: 356/399, 356/400, 356/401, 382/103, 382/151, 382/294, 702/150
• US Class Current: 356/401
• CPC Class Codes: G03F 9/7076 Mark details, e.g. phase grating mark, temporary mark
• CPC Class Codes: G03F 9/708 Mark formation
• CPC Class Codes: G03F 9/7084 Position of mark on substrate, i.e. position in (x, y, z) of mark, e.g. buried or resist covered mark, mark on rearside, at the substrate edge, in the circuit area, latent image mark, marks in plural levels
• 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 7/30 Determination of transform parameters for the alignment of images, i.e. image registration
• CPC Class Codes: G06T 7/73 using feature-based methods
• CPC Class Codes: G06V 10/245 by locating a pattern; Special marks for positioning

Abstract

An article of manufacture bearing an alignment target having at least one of the following attributes: it has no significant rotational symmetry; it has no significant orientation self-similarity or size self-similarity; it is not primarily composed of circles, circular arcs, straight lines, or right angles; and it may have other unique attributes. In one embodiment, the specific alignment targets are shapes consisting of at least one “generalized polar polygon.” Such a figure will include radial lines, circular arcs, and spiral segments when drawn in the Cartesian plane. In another embodiment, the specific alignment targets are members of a family of “fan” shapes.

Claims

1. An alignment target comprising:

a target characterized by a fan shape;

the target having a plurality of blades; and

at least one blade of the plurality of blades being different from another blade in the plurality of blades.

2. The alignment target according to claim 1 wherein:

at least one blade of the plurality of blades having a width different from the width of at least one other blade in the plurality of blades.

3. The alignment target according to claim 1, further comprising:

at least one blade of the plurality of blades having a width different from the width of all other blades in the plurality of blades.

4. The alignment target according to claim 1, wherein:

each of the plurality of blades having a width different from the width of all other blades in the plurality of blades.

5. An alignment target comprising:

a target characterized by a fan shape;

the target having a plurality of blades; and

at least one of the plurality of blades including at least one hole.

6. The alignment target according to claim 5, wherein:

each of the plurality of blades includes at least one hole.

7. An alignment target comprising:

a target characterized by a fan shape;

the target having a plurality of blades separated by a like number of gaps to provide a plurality of gaps; and

at least one of the plurality of gaps having a width different from the width of at least one other gap in the plurality of gaps.

8. The alignment target according to claim 7, wherein:

at least one of the plurality of gaps having a width different from the width of all other gaps in the plurality of gaps.

9. The alignment target according to claim 7, wherein:

each of the plurality of gaps having a width different from the width of all other gaps in the plurality of gaps.

10. An alignment target comprising:

a target characterized by a fan shape;

the target having a plurality of blades; and

at least one of the plurality of blades having a non-zero skew.

11. The alignment target according to claim 10 further comprising:

the skew of the at least one of the plurality of blades is different from a skew of at least one other blade in the plurality of blades.

12. The alignment target according to claim 10 further comprising:

the skew of the at least one of the plurality of blades being different from a skew of all the other blades in the plurality of blades.

13. The alignment target according to claim 10, wherein:

each of the plurality of blades having a skew different from the skew of all other blades in the plurality of blades.

14. An alignment target comprising:

a target characterized by a fan shape;

the target having a plurality of blades; and

at least one of the plurality of blades having a non-zero spiral.

15. The alignment target according to claim 14 further comprising:

the spiral of the at least one of the plurality of blades being different from a spiral of at least one other blade in the plurality of blades.

16. The alignment target according to claim 14 further comprising:

the spiral of the at least one blade in the plurality of blades being different from the spiral of all other blades in the plurality of blades.

17. The alignment target according to claim 14, wherein:

each of the plurality of blades having a spiral different from the spiral of all other blades in the plurality of blades.