Metrology method, target and substrate

• US 10,718,604 B2
• Filed: 07/10/2019
• Issued: 07/21/2020
• Est. Priority Date: 08/29/2014
• Status: Active Grant

• Current Assignee: ASML Netherlands BV (ASML Holding NV)
• Original Assignee: ASML Netherlands BV (ASML Holding NV)
• Inventors: Bhattacharyya, Kaustuve, Van Buel, Henricus Wilhelmus Maria, Fouquet, Christophe David, Smilde, Hendrik Jan Hidde, Van Der Schaar, Maurits, Den Boef, Arie Jeffrey, Van Haren, Richard Johannes Franciscus, Liu, Xing Lan, Beltman, Johannes Marcus Maria, Fuchs, Andreas, Adam, Omer Abubaker Omer, Kubis, Michael, Jak, Martin Jacobus Johan
• Primary Examiner(s): Pham, Hoa Q
• Application Number:
  US16/507,297
• Publication Number:
  US 20190346256A1
• Time in Patent Office: 377 Days
• CPC Class Codes: G01B 11/14 for measuring distance or clearance between spaced objects or spaced apertures G01B11/26 takes precedence; rangefinders G01C3/00
• CPC Class Codes: G03F 7/70633 Overlay, i.e. relative alignment between patterns printed by separate exposures in different layers, or in the same layer in multiple exposures or stitching
• CPC Class Codes: G03F 7/70683 Mark designs

Abstract

A diffraction measurement target that has at least a first sub-target and at least a second sub-target, and wherein (1) the first and second sub-targets each include a pair of periodic structures and the first sub-target has a different design than the second sub-target, the different design including the first sub-target periodic structures having a different pitch, feature width, space width, and/or segmentation than the second sub-target periodic structure or (2) the first and second sub-targets respectively include a first and second periodic structure in a first layer, and a third periodic structure is located at least partly underneath the first periodic structure in a second layer under the first layer and there being no periodic structure underneath the second periodic structure in the second layer, and a fourth periodic structure is located at least partly underneath the second periodic structure in a third layer under the second layer.

Claims

1. A method comprising:

illuminating a measurement target on a substrate with radiation, wherein;

the measurement target comprises at least a first sub-target and a second sub-target,

each of the first sub-target and the second sub-target has a first periodic structure having features extending in a first direction and a second periodic structure having features extending in a second different direction,

the first sub-target at least partly overlays a third sub-target and the second sub-target at least partly overlays a fourth sub-target, and

the first sub-target has a different design than the third sub-target and/or the second sub-target has a different design than the fourth sub-target; and

detecting radiation scattered by at least the first and second sub-targets to obtain for the measurement target a measurement representing a parameter of a lithographic process.

2. The method of claim 1, wherein the first sub-target has a different pitch, feature width, or space width than the third sub-target and/or the second sub-target has a different pitch, feature width, or space width than the fourth sub-target.

3. The method of claim 1, wherein the first sub-target has a different design than the second sub-target.

4. The method of claim 3, wherein the first sub-target has a different pitch, feature width, or space width than the second sub-target.

5. The method of claim 1, wherein the third sub-target has a different design than the fourth sub-target.

6. The method of claim 5, wherein the third sub-target has a different pitch, feature width, or space width than the fourth sub-target.

7. The method of claim 1, wherein the first and second periodic structures of the second sub-target meet at a center of the measurement target and the first and second periodic structures of the first sub-target are arranged around a periphery of the first and second periodic structures of the second sub-target.

8. The method of claim 7, wherein a length and width of each of the first and second periodic structures of the first sub-target is substantially the same as a length and width of each of the first and second periodic structures of the second sub-target.

9. The method of claim 1, wherein the first direction and the second different direction are substantially perpendicular.

10. The method of claim 1, wherein the parameter of the lithographic process is overlay.

11. The method of claim 1, wherein a bias difference is provided between the first sub-target and the second sub-target.

12. The method of claim 1, wherein the illuminating comprising illuminating a measurement spot on the measurement target that covers at one time at least part of each of the first and second periodic structures of the first sub-target and the first and second periodic structures of the second sub-target.

13. The method of claim 1, wherein the third and fourth sub-targets each comprise periodic structures.

14. The method of claim 1, wherein the detecting comprises detecting radiation scattered by at least the first, second, third and fourth sub-targets to obtain for the measurement target a measurement representing the parameter of the lithographic process.

15. The method of claim 1, wherein the detecting radiation comprises forming a dark field image of at least the first and second sub-targets.

16. A non-transitory computer program product comprising machine-readable instructions therein, the instructions, upon execution by a computer system, configured to cause the computer system to at least cause performance of the method of claim 1.

17. A non-transitory computer program product comprising machine-readable instructions therein, the instructions, upon execution by a computer system, configured to cause the computer system to at least:

obtain a result from detection of radiation scattered by a measurement target on a substrate, wherein;

the measurement target comprises at least a first sub-target and a second sub-target,

each of the first sub-target and the second sub-target has a first periodic structure having features extending in a first direction and a second periodic structure having features extending in a second different direction,

the first sub-target at least partly overlays a third sub-target and the second sub-target at least partly overlays a fourth sub-target, and

the first sub-target has a different design than the third sub-target and/or the second sub-target has a different design than the fourth sub-target; and

determine, from the result and for the measurement target, a measurement representing a parameter of a lithographic process.

18. A measurement target for determination of a parameter of a lithographic process, the target comprising:

at least a first sub-target and a second sub-target, wherein;

each of the first sub-target and the second sub-target has a first periodic structure having features extending in a first direction and a second periodic structure having features extending in a second different direction,

the first sub-target at least partly overlays a third sub-target and the second sub-target at least partly overlays a fourth sub-target, and

the first sub-target has a different design than the third sub-target and/or the second sub-target has a different design than the fourth sub-target.

19. The target of claim 18, wherein the first sub-target and/or second sub-target has a different pitch, feature width, or space width than the third sub-target and/or fourth sub-target.

20. The target of claim 18, wherein the first sub-target has a different design than the second sub-target.

21. The target of claim 18, wherein the target is a dark-field image-based target.

22. A substrate comprising the target of claim 18.