Metrology method, target and substrate

• US 10,133,188 B2
• Filed: 12/21/2016
• Issued: 11/20/2018
• Est. Priority Date: 12/23/2015
• Status: Active Grant

• Current Assignee: ASML Netherlands BV (ASML Holding NV)
• Original Assignee: ASML Netherlands BV (ASML Holding NV)
• Inventors: Jak, Martin Jacobus Johan, Den Boef, Arie Jeffrey, Ebert, Martin
• Primary Examiner(s): Kim, Peter B
• Application Number:
  US15/387,431
• Publication Number:
  US 20170184977A1
• Time in Patent Office: 699 Days
• Field of Search: 355 67
• CPC Class Codes: G01B 11/26 for measuring angles or tapers; for testing the alignment of axes
• CPC Class Codes: G01N 21/21 Polarisation-affecting properties G01N21/19 takes precedence
• CPC Class Codes: G01N 21/4788 Diffraction for sizing particles G01N15/0205
• CPC Class Codes: G01N 21/9501 Semiconductor wafers manufacturing processes per se of semiconductor devices implementing a measuring step H01L22/10
• CPC Class Codes: G02B 27/4255 for alignment or positioning purposes optical displacement encoding scales G01D5/347
• CPC Class Codes: G02B 27/4272 having plural diffractive elements positioned sequentially along the optical path
• CPC Class Codes: G02B 5/1819 Plural gratings positioned on the same surface, e.g. array of gratings plural diffractive elements positioned sequentially along the optical path G02B27/4272
• CPC Class Codes: G02B 5/1823 in an overlapping or superposed manner
• CPC Class Codes: G03F 7/70191 Optical correction elements, filters or phase plates for controlling intensity, wavelength, polarisation, phase or the like
• CPC Class Codes: G03F 7/70616 Monitoring the printed patterns
• 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
• CPC Class Codes: G03F 7/7085 Detection arrangement, e.g. detectors of apparatus alignment possibly mounted on wafers, exposure dose, photo-cleaning flux, stray light, thermal load
• CPC Class Codes: G03F 9/7049 Technique, e.g. interferometric
• CPC Class Codes: G03F 9/7076 Mark details, e.g. phase grating mark, temporary mark

Abstract

A method, involving illuminating at least a first periodic structure of a metrology target with a first radiation beam having a first polarization, illuminating at least a second periodic structure of the metrology target with a second radiation beam having a second different polarization, combining radiation diffracted from the first periodic structure with radiation diffracted from the second periodic structure to cause interference, detecting the combined radiation using a detector, and determining a parameter of interest from the detected combined radiation.

Claims

1. A method, comprising:

illuminating at least a first periodic structure of a metrology target with a first radiation beam having a first polarization;

illuminating at least a second periodic structure of the metrology target with a second radiation beam having a second different polarization;

combining radiation diffracted from the first periodic structure with radiation diffracted from the second periodic structure to cause interference;

detecting the combined radiation using a detector; and

determining a parameter of interest from a value of an intensity difference or ratio determined using the detected combined radiation.

2. The method of claim 1, wherein the second polarization is substantially orthogonal to the first polarization.

3. The method of claim 1, further comprising using a beam splitter to split an incoming beam into the first radiation beam having the first polarization and the second radiation beam having the second polarization.

4. The method of claim 1, wherein the first and second radiation beams are coherent with respect to each other.

5. The method of claim 1, wherein a center of a spot of the first radiation beam on the metrology target is laterally displaced from a center of a spot of the second radiation beam on the metrology target.

6. The method of claim 5, wherein at least part of the second periodic structure does not overlie at least part of the first periodic structure and the center of the spot of the first radiation beam is incident on the at least part of the first periodic structure and the center of the spot of the second radiation beam is not incident on the at least part of the first periodic structure.

7. The method of claim 1, wherein the angle of incidence of the first radiation beam on the metrology target is different than the angle of incidence of the second radiation beam on the metrology target.

8. The method of claim 1, further comprising changing an intensity ratio between the first and second radiation beams.

9. The method of claim 1, further comprising changing a phase between the first and second radiation beams.

10. The method of claim 1, further comprising passing the combined radiation through a polarizer or retarder prior to detection.

11. The method of claim 1, wherein comprising determining the parameter of interest comprises determining a parameter of interest for the target from the combined radiation and determining a parameter of interest specific to the first periodic structure and/or the second periodic structure from the combined radiation.

12. A method of manufacturing devices wherein a device pattern is applied to a series of substrates using a patterning process, the method including inspecting at least a diffraction metrology target formed as part of or beside the device pattern on at least one of the substrates using the method of claim 1, and controlling the patterning process for later substrates in accordance with the result of the method.

13. A metrology apparatus comprising:

an optical system configured to provide a first radiation beam having a first polarization and a second radiation beam having a second polarization onto a metrology target having a plurality of periodic structures;

a detector configured to detect radiation from the first and second radiation beams diffracted by the periodic structures, wherein the diffracted radiation from the periodic structures is combined and interferes; and

a control system configured to determine a parameter of interest from a value of an intensity difference or ratio determined using the detected combined diffracted radiation.

14. The apparatus of claim 13, wherein the second polarization is substantially orthogonal to the first polarization.

15. The apparatus of claim 13, wherein the first and second radiation beams are coherent with respect to each other.

16. The apparatus of claim 13, wherein the optical system comprises a beam splitter configured to split an incoming beam into the first radiation beam having the first polarization and the second radiation beam having the second polarization.

17. The apparatus claim 13, wherein a center of a spot of the first radiation beam on the metrology target is laterally displaced from a center of a spot of the second radiation beam on the metrology target.

18. The apparatus of claim 17, wherein at least part of the second periodic structure does not overlie at least part of the first periodic structure and the center of the spot of the first radiation beam is incident on the at least part of the first periodic structure and the center of the spot of the second radiation beam is not incident on the at least part of the first periodic structure.

19. The apparatus of claim 13, wherein the angle of incidence of the first radiation beam on the metrology target is different than the angle of incidence of the second radiation beam on the metrology target.

20. The apparatus of claim 13, further comprising a polarizer or retarder configured to change an intensity ratio between the first and second radiation beams.

21. The apparatus of claim 13, further comprising a retarder configured to change a phase between the first and second radiation beams.

22. The apparatus of claim 13, further comprising a polarizer or retarder configured to process the combined radiation prior to detection.

23. The apparatus of claim 13, wherein the control system configured to determine a parameter of interest from the detected combined is configured to determine a parameter of interest for the target from the combined radiation and determine a parameter of interest specific to the first periodic structure and/or the second periodic structure from the combined radiation.

24. A non-transitory computer program product comprising machine-readable instructions for causing a processor to:

cause illumination of at least a first periodic structure of a metrology target with a first radiation beam having a first polarization;

cause illumination of at least a second periodic structure of the metrology target with a second radiation beam having a second different polarization, wherein radiation diffracted from the first periodic structure combines with radiation diffracted from the second periodic structure to cause interference and wherein the first radiation beam and the second radiation beam form a single beam spot on the metrology target or overlapping beam spots on the metrology target;

cause detection of the combined radiation using a detector; and

determine a parameter of interest from the detected combined radiation.

25. A system comprising:

an inspection apparatus configured to provide a beam on a diffraction metrology target on a substrate and to detect radiation diffracted by the metrology target to determine a parameter of interest of a patterning process; and

the non-transitory computer program product of claim 24.