Systems and methods for a wafer inspection system using multiple angles and multiple wavelength illumination

• US 20010052975A1
• Filed: 06/26/2001
• Published: 12/20/2001
• Est. Priority Date: 09/19/1997
• Status: Active Grant

• Current Assignee: Kla-Tencor Technologies Corporation (KLA Corporation)
• Original Assignee: Kla-Tencor Technologies Corporation (KLA Corporation)
• Inventors: Vaez-Iravani, Mehdi, Stokowski, Stanley E., Biellak, Steve
• Granted Patent: US 6,956,644 B2
• Time in Patent Office: Days
• US Class Current: 356/237.3
• CPC Class Codes: G01N 2021/8825 Separate detection of dark field and bright field
• CPC Class Codes: G01N 21/47 Scattering, i.e. diffuse reflection G01N21/25, G01N21/41 take precedence G01N21/55 takes precedence
• CPC Class Codes: G01N 21/474 Details of optical heads therefor, e.g. using optical fibres
• CPC Class Codes: G01N 21/84 Systems specially adapted for particular applications
• CPC Class Codes: G01N 21/88 Investigating the presence of flaws or contamination
• CPC Class Codes: G01N 21/8806 Specially adapted optical and illumination features
• CPC Class Codes: G01N 21/95 characterised by the material or shape of the object to be examined G01N21/89 - G01N21/91, G01N21/94 take precedence
• 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: H01L 22/12 for structural parameters, e.g. thickness, line width, refractive index, temperature, warp, bond strength, defects, optical inspection, electrical measurement of structural dimensions, metallurgic measurement of diffusions electrical measurement of diffusions H01L22/14

Abstract

A method for detecting an anomaly on a top surface of a substrate comprises directing a first radiation beam having a first wavelength at the top surface of the substrate at a first angle measured from normal, and directing a second radiation beam having a second wavelength at the top surface of the substrate at a second angle measured from normal, wherein the second wavelength is not equal to the first wavelength. The method then comprises detecting scattered radiation from the first radiation beam and the second radiation beam to detect the presence of particles or COPs, and to differentiate between the two. Differences in the scattered radiation detected from the first radiation beam and from the second radiation beam provide the data needed to differentiate between particles and COPs.

Claims

1. A method for detecting an anomaly on a top surface of a substrate, or within the substrate, comprising:

directing a first radiation beam having a first wavelength at the top surface of the substrate at a first angle measured from the normal direction to the top surface;

directing a second radiation beam having a second wavelength at the top surface of the substrate at a second angle measured from the normal direction to the top surface, wherein the second wavelength is not equal to the first wavelength;

detecting radiation from the first radiation beam; and

detecting radiation from the second radiation beam.

2. The method of

claim 1

, further comprising causing relative motion between the first and second radiation beams and the top surface of the substrate.

3. The method of

claim 1

, further comprising documenting the presence of an anomaly if the detected radiation shows that the first radiation beam was scattered upon interacting with the top surface.

4. The method of

claim 1

, further comprising documenting the presence of an anomaly if the detected radiation shows that the second radiation beam was scattered upon interacting with the top surface.

5. The method of

claim 1

, further comprising comparing radiation detected from the first radiation beam to radiation detected from the second radiation beam to determine whether the anomaly comprises a COP or a particle.

6. The method of

claim 1

, wherein the first wavelength is around 266 nanometers.

7. The method of

claim 1

, wherein the first wavelength is around 355 nanometers.

8. The method of

claim 1

, wherein the first wavelength is a wavelength in the ultraviolet spectrum of radiation.

9. The method of

claim 1

, wherein the second wavelength is around 532 nanometers.

10. The method of

claim 1

, wherein the second wavelength is a wavelength in the visible spectrum of radiation.

11. The method of

claim 1

, wherein the first wavelength is around 266 nanometers and the second wavelength is around 532 nanometers.

12. The method of

claim 1

, wherein the first wavelength is around 355 nanometers and the second wavelength is around 532 nanometers.

13. The method of

claim 1

, wherein the first wavelength is in the ultra-violet spectrum of radiation and the second wavelength is in the visible spectrum of radiation.

14. The method of

claim 1

, wherein the first angle is around 70 degrees.

15. The method of

claim 1

, wherein the second angle is around zero degrees.

16. The method of

claim 1

, wherein the directing of a first radiation beam and the directing of a second radiation beam are performed simultaneously.

17. The method of

claim 1

, wherein the detecting of radiation from the first radiation beam and the detecting of radiation from the second radiation beam are performed simultaneously.

18. The method of

claim 1

, wherein the first radiation beam comprises a laser beam.

19. The method of

claim 1

, wherein the second radiation beam comprises a laser beam.

20. The method of

claim 1

, wherein the detecting of radiation from the second radiation beam comprises detecting scattered radiation from the second radiation beam and avoiding reflected radiation from the second radiation beam.

21. The method of

claim 2

, further comprising documenting the presence of an anomaly if the detected radiation shows an increase in the amount of scattered radiation produced by the first radiation beam.

22. The method of

claim 2

, further comprising documenting the presence of an anomaly if the detected radiation shows an increase in the amount of scattered radiation produced by the second radiation beam.

41. The method of

claim 1

, further comprising comparing radiation detected from the first radiation beam to radiation detected from the second radiation beam to determine whether the anomaly is located on the top surface or below the top surface of the substrate.

23. A method for detecting an anomaly on a top surface of a substrate, or within the substrate, comprising:

directing a first radiation beam having a first wavelength at the top surface of the substrate at a first angle measured from normal, wherein the first wavelength is in the ultraviolet spectrum of radiation;

directing a second radiation beam having a second wavelength at the top surface of the substrate at a second angle measured from normal, wherein the second wavelength is in the visible spectrum of radiation;

detecting radiation from the first and second radiation beams;

causing relative motion between the first and second radiation beams and the top surface of the substrate; and

documenting the presence of an anomaly if the detected radiation shows an increase in the amount of scattered radiation produced by the first radiation beam or the second radiation beam.

24. A system for detecting an anomaly on a top surface of a substrate, or within the substrate, comprising:

a radiation source operable to emit a first wavelength radiation and a second wavelength radiation;

at least one objective operable to focus the first wavelength radiation into a first radiation beam and to focus the second wavelength radiation into a second radiation beam; and

a detector mounted to detect radiation.

25. The system of

claim 24

, further comprising a beamsplitter to separate the first radiation beam from the second radiation beam.

26. The system of

claim 24

, further comprising a collector operable to collect radiation and focus the radiation onto the detector.

27. The system of

claim 24

, wherein the radiation source is provided by a laser source.

28. The system of

claim 24

, wherein the first wavelength is around 266 nanometers.

29. The system of

claim 24

, wherein the first wavelength is around 355 nanometers.

30. The system of

claim 24

, wherein the first wavelength is a wavelength in the ultraviolet spectrum of radiation.

31. The system of

claim 24

, wherein the second wavelength is around 532 nanometers.

32. The system of

claim 24

, wherein the second wavelength is a wavelength in the visible spectrum of radiation.

33. The system of

claim 24

, wherein the first wavelength is around 266 nanometers and the second wavelength is around 532 nanometers.

34. The system of

claim 24

, wherein the first wavelength is around 355 nanometers and the second wavelength is around 532 nanometers.

35. The system of

claim 24

, wherein the first wavelength is a wavelength in the ultraviolet spectrum of radiation and the second wavelength is a wavelength in the visible spectrum of radiation.

36. The system of

claim 25

, further comprising at least one mirror mounted to direct the first radiation beam at the top surface at a first angle measured from normal and to direct the second radiation beam at the top surface at a second angle measured from normal.

37. The system of

claim 25

, wherein the first angle is around 70 degrees.

38. The system of

claim 25

, wherein the second angle is around zero degrees.

39. The system of

claim 27

, wherein the laser source is a solid-state laser.

40. The system of

claim 27

, wherein the laser source can vary the wavelength of emitted radiation using one or more crystals.

42. A method for detecting an anomaly only on a top surface of a substrate, comprising:

directing a first ultraviolet radiation beam at the top surface of the substrate at a first angle measured from the normal direction to the top surface;

directing a second ultraviolet radiation beam at the top surface of the substrate at a second angle measured from the normal direction to the top surface;

detecting ultraviolet radiation from the first ultraviolet radiation beam; and

detecting ultraviolet radiation from the second ultraviolet radiation beam.

43. The method of

claim 42

, wherein the first and second ultraviolet radiation beams have a wavelength of around 266 nm.

44. The method of

claim 42

, wherein the first and second ultraviolet radiation beams have a wavelength of around 355 nm.

45. The method of

claim 42

, wherein the substrate comprises a silicon-on-insulator wafer.