Adjustment of a metrology apparatus or a measurement thereby based on a characteristic of a target measured

Patent metadata

Field	Value
Publication number	US-10996571-B2
Application number	US-202016856128-A
Country	US
Kind code	B2
Filing date	Apr 23, 2020
Priority date	Dec 17, 2015
Publication date	May 4, 2021
Grant date	May 4, 2021

Abstract

A method of adjusting a metrology apparatus, the method including: spatially dividing an intensity distribution of a pupil plane of the metrology apparatus into a plurality of pixels; and reducing an effect of a structural asymmetry in a target on a measurement by the metrology apparatus on the target, by adjusting intensities of the plurality of pixels.

First claim

The invention claimed is:

1. A method of adjusting a metrology apparatus, the method comprising:
setting or adjusting a parameter of the metrology apparatus for measuring a target or of a measurement by the metrology apparatus of the target, to a value based on a characteristic of the target, the characteristic comprising a structural asymmetry within the target or a value representing a location of the target on a substrate.

2. The method of claim 1 , wherein the measurement is one or more selected from: a measurement of overlay, a measurement of focus, and/or a measurement of aberration.

3. The method of claim 1 , wherein the parameter is one or more selected from: an intensity at an illumination pupil of the metrology apparatus, a polarization at an illumination pupil of the metrology apparatus, a wavelength at an illumination pupil of the metrology apparatus, a bandwidth at an illumination pupil of the metrology apparatus, an intensity at a detection pupil of the metrology apparatus, a polarization at a detection pupil of the metrology apparatus, a wavelength at a detection pupil of the metrology apparatus, and/or a bandwidth at a detection pupil of the metrology apparatus.

4. The method of claim 1 , wherein the parameter is a characteristic of projection optics of the metrology apparatus and/or a characteristic of radiation illumination of the metrology apparatus.

5. The method of claim 1 , wherein the setting or adjusting the parameter impacts a quality of the measurement of the target.

6. The method of claim 5 , wherein the quality represents detectability of the target, accuracy of the measurement, and/or robustness of the measurement.

7. The method of clause 20, wherein the setting or adjusting the parameter comprises computing a cost function that represents the quality and is a function of the parameter.

8. The method of claim 7 , wherein the cost function represents contrast of an image of the target.

9. The method of claim 7 , wherein the setting or adjusting the parameter further comprises finding a value of the parameter that locally or globally minimizes or maximizes the cost function.

10. The method of claim 7 , wherein the cost function is constrained.

11. The method of claim 7 , wherein the cost function is a function of the characteristic of the target.

12. The method of claim 1 , further comprising adjusting the characteristic of the target.

13. The method of claim 1 , wherein the characteristic of the target comprises a value representing a location of the target on a substrate.

14. The method of claim 1 , wherein the characteristic of the target comprises a structural asymmetry within the target.

15. A computer program product comprising a non-transitory computer-readable medium having instructions therein, the instructions, upon execution by a computer system, configured to cause the computer system to at least:
set or adjust a parameter of a metrology apparatus for measuring a target or of a measurement by the metrology apparatus of the target, to a value based on a characteristic of the target, the characteristic comprising a structural asymmetry within the target or a value representing a location of the target on a substrate.

16. The computer program product of claim 15 , wherein the parameter is one or more selected from: an intensity at an illumination pupil of the metrology apparatus, a polarization at an illumination pupil of the metrology apparatus, a wavelength at an illumination pupil of the metrology apparatus, a bandwidth at an illumination pupil of the metrology apparatus, an intensity at a detection pupil of the metrology apparatus, a polarization at a detection pupil of the metrology apparatus, a wavelength at a detection pupil of the metrology apparatus, and/or a bandwidth at a detection pupil of the metrology apparatus.

17. The computer program product of claim 15 , wherein the setting or adjusting of the parameter impacts a quality of the measurement of the target.

18. The computer program product of claim 17 , wherein the instructions configured to cause the computer system to set or adjust the parameter are further configured to compute a cost function that represents the quality and is a function of the parameter.

19. The computer program product of claim 15 , wherein the characteristic of the target comprises a value representing a location of the target on a substrate.

20. The computer program product of claim 15 , wherein the characteristic of the target comprises a structural asymmetry within the target.

21. A method comprising:
setting or adjusting a parameter of a metrology apparatus for measuring a target or of a measurement by the metrology apparatus of the target, to a value set or adjusted based on a characteristic of the target, the characteristic comprising a structural asymmetry within the target; and
measuring the target with the metrology apparatus.

Assignees

• Asml Netherlands Bv

Inventors

• Socha Robert John
• Den Boef Arie Jeffrey
• Pandey Nitesh

Classifications

• G03F7/706851

  Detection branch, e.g. detector arrangements, polarisation control, wavelength control or dark/bright field detection · CPC title

• G03F7/70633 Primary

  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 title

• G01N21/956

  Inspecting patterns on the surface of objects {(contactless testing of electronic circuits G01R31/308; testing currency G07D; manufacturing processes per se of semiconductor devices implementing a measuring step H10P74/20)} · CPC title

• G03F7/70641 Primary

  Focus · CPC title

• G03F7/706

  Aberration measurement · CPC title