POLARIZATION MEASUREMENTS OF METROLOGY TARGETS AND CORRESPONDING TARGET DESIGNS

• US 20160178351A1
• Filed: 11/23/2015
• Published: 06/23/2016
• Est. Priority Date: 06/27/2013
• Status: Active Grant

• Current Assignee: KLA-Tencor Corporation
• Original Assignee: KLA-Tencor Corporation
• Inventors: LOEVSKY, Barry, HILL, Andrew, AMIT, Eran, MANASSEN, Amnon, AMIR, Nuriel, LEVINSKI, Vladimir, VOLKOVICH, Roie
• Granted Patent: US 10,458,777 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: G01B 11/06 for measuring thickness ; e.g. of sheet material thickness measurement by thermal means G01B21/085
• CPC Class Codes: G01B 11/272 using photoelectric detection means
• CPC Class Codes: G01B 2210/56 Measuring geometric parameters of semiconductor structures, e.g. profile, critical dimensions or trench depth
• CPC Class Codes: G01B 2290/70 Using polarization in the interferometer
• CPC Class Codes: G01N 2021/8848 Polarisation of light
• CPC Class Codes: G01N 21/9501 Semiconductor wafers manufacturing processes per se of semiconductor devices implementing a measuring step H01L22/10
• CPC Class Codes: G01N 21/956 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 H01L22/10
• CPC Class Codes: G06F 30/392 Floor-planning or layout, e.g. partitioning or placement
• CPC Class Codes: G06F 30/398 Design verification or optimisation, e.g. using design rule check [DRC], layout versus schematics [LVS] or finite element methods [FEM] optical proximity correction [OPC] design processes G03F1/36
• CPC Class Codes: H01L 22/30 Structural arrangements specially adapted for testing or measuring during manufacture or treatment, or specially adapted for reliability measurements

Abstract

Targets, target elements and target design method are provided, which comprise designing a target structure to have a high contrast above a specific contrast threshold to its background in polarized light while having a low contrast below the specific contrast threshold to its background in non-polarized light. The targets may have details at device feature scale and be compatible with device design rules yet maintain optical contrast when measured with polarized illumination and thus be used effectively as metrology targets. Design variants and respective measurement optical systems are likewise provided.

Claims

1. A method comprising:

designing a target structure to have a high contrast above a specific contrast threshold to its background in polarized light while having a low contrast below the specific contrast threshold to its background in non-polarized light, wherein the designing is carried out by at least one computer processor.

2. The method of claim 1, further comprising:

designing the target structure to be fully process compatible with respect to a production process thereof.

3. The method of claim 1, further comprising:

configuring the target structure to have features which are perpendicular to background features of the target structure.

4. The method of claim 1, further comprising:

designing additional layers in a region of the target structure to maintain or to enhance the contrast of the target structure to its background in polarized light.

5. The method of claim 1, further comprising:

spacing the target structure from background features thereof to a specified extent.

6. The method of claim 1, further comprising:

producing the designed target structure.

7. The method of claim 2, further comprising:

producing the designed target structure.

8. The method of claim 3, further comprising:

producing the designed target structure.

9. The method of claim 4, further comprising:

producing the designed target structure.

10. The method of claim 5, further comprising:

producing the designed target structure.

11. The method of claim 5, further comprising:

measuring the target structure in polarized light to distinguish it from its background.

12. The method of claim 11, further comprising:

measuring the target structure repeatedly under varying illumination conditions and deriving additional measurement data from the multiple measurements.

13. The method of claim 11, further comprising:

adjusting measurement conditions for each layer to enhance the contrast between the target structure contrast and its background.

14. The method of claim 12, further comprising:

measuring first order diffraction patterns after removing zeroth order diffraction patterns.

15. The method of claim 11, wherein the measuring is carried out using at least one of:

coupled polarizers, alternating polarizers in an optical path of the measurement, an interferometer, variable retarder polarizers, a zero order blocker at a pupil plane and polarized light sources.

16. A computer program product comprising:

a computer readable storage medium having computer readable program embodied therewith, the computer readable program configured to carry out the method of claim 1.

17. A target design file, designed or produced according to the method of claim 1.

18. A metrology target designed, produced or measured according to the method of claim 1.

19. A metrology target comprising:

a target structure arranged to have a high contrast above a specific contrast threshold to a background in polarized light while having a low contrast below the specific contrast threshold to the background in non-polarized light, and further arranged to be fully process-compatible with respect to a production process thereof.

20. The metrology target of claim 19, wherein the target structure comprises features which are perpendicular to background features.

21. The metrology target of claim 19, further comprising additional layers in a region of the target structure to maintain or to enhance the contrast of the target structure to its background in polarized light.

22. The metrology target of claim 19, wherein the target structure is spaced from background features thereof to a specified extent.

23. Metrology measurements of the metrology target of claim 19.

24. Metrology measurements of the metrology target of claim 20.

25. Metrology measurements of the metrology target of claim 21.

26. Metrology measurements of the metrology target of claim 22.

27. The metrology measurements of claim 23, carried out repeatedly under varying illumination conditions and additional measurement data derived from the multiple measurements.

28. The metrology measurements of claim 24, carried out repeatedly under varying illumination conditions and additional measurement data derived from the multiple measurements.

29. The metrology measurements of claim 25, carried out repeatedly under varying illumination conditions and additional measurement data derived from the multiple measurements.

30. The metrology measurements of claim 26, carried out repeatedly under varying illumination conditions and additional measurement data derived from the multiple measurements.