Optical coupling apparatus for a dual column charged particle beam tool for imaging and forming silicide in a localized manner

• US 20060076503A1
• Filed: 09/08/2005
• Published: 04/13/2006
• Est. Priority Date: 10/12/2004
• Status: Active Grant

• Current Assignee: DCG Systems Incorporated (Thermo Fisher Scientific Incorporated)
• Original Assignee: Credence Systems Corporation (COHU Incorporated)
• Inventors: Tsao, Chun-Cheng
• Granted Patent: US 7,612,321 B2
• Time in Patent Office: Days
• US Class Current: 250/396.R
• CPC Class Codes: H01J 2237/2482 Optical means
• CPC Class Codes: H01J 2237/31749 Focused ion beam
• CPC Class Codes: H01J 37/228 whereby illumination or light collection take place in the same area of the discharge
• CPC Class Codes: H01J 37/3056 for microworking, e. g. etching of gratings or trimming of electrical components
• CPC Class Codes: H01L 21/76892 modifying the pattern
• CPC Class Codes: H01L 21/76898 formed through a semiconductor substrate

Abstract

An optical coupling apparatus for a dual column charged particle beam tool allowing both optical imaging of an area of an integrated circuit, as well as localized heating of the integrated circuit to form silicide. In one embodiment, optical paths from a whitelight source and a laser source are coupled together by way of first and second beam splitters so that a single optical port of the dual column tool may be utilized for both imaging and heating. In another embodiment, a single laser source is employed to provide both illumination for standard microscopy-type imaging, as well as localized heating. In a third embodiment, a single laser source provides heating along with localized illumination for confocal scanning microscopy-type imaging.

Claims

1. A charged particle beam tool having an optical port comprising:

a whitelight source;

a first beam splitter optically coupled with the whitelight source and the optical port;

an image sensor;

a laser source; and

a second beam splitter optically coupled with the laser source, the first beam splitter, and the image sensor.

2. The apparatus of claim 1, further comprising:

a fiber light guide optically coupling the whitelight source and a condenser lens;

an aperture stop optically coupled with the condenser lens, the aperture stop for controlling a size of the whitelight source;

a field stop optically coupled with the aperture stop for controlling a imaging size of the whitelight source; and

a field lens optically coupled with the condenser lens and an objective lens.

3. The apparatus of claim 2, further comprising:

an optical bandpass filter optically coupled with condenser lens and the aperture stop to select a wavelength for imaging.

4. The apparatus of claim 3, the optical bandpass filter comprising a filter wheel, the filter wheel comprising at least one filter window.

5. The apparatus of claim 1, further comprising:

a fiber coupling lens optically coupled with the laser source;

a first end of an optical fiber optically coupled with the fiber coupling lens; and

a collimating lens optically coupled with a second end of the optical fiber and the second beam splitter.

6. The apparatus of claim 1, further comprising a beam trap optically coupled with the first beam splitter.

7. The apparatus of claim 1, further comprising a beam trap optically coupled with the second beam splitter.

8. The apparatus of claim 1, the image sensor comprising at least one of a charge-coupled device camera, a focal plane array camera, and a CMOS camera.

9. The apparatus of claim 1, wherein light from the whitelight source is adapted to image an area of an integrated circuit optically coupled with the charged particle beam tool.

10. The apparatus of claim 1, wherein light from the laser source is adapted to heat an area of an integrated circuit optically coupled with the charged particle beam tool.

11. A charged particle beam tool comprising the apparatus of claim 1.

12. An apparatus for optically coupling a laser source to a dual-column charged particle beam tool having an optical port, the apparatus comprising:

a configurable laser light converter optically coupled with the laser source, the configurable laser light converter comprising;

a first configuration wherein light provided by the laser source is converted to a first light beam comprising a first width; and

a second configuration wherein light provided by the laser source is converted to a second light beam comprising a second width narrower than the first width;

a first beam splitter optically coupled with the optical port and the configurable laser light converter; and

an image sensor optically coupled with the first beam splitter.

13. The apparatus in claim 12, wherein the first width defines a large illumination area on an integrated circuit.

14. The apparatus in claim 12, wherein the second width defines a focused spot on an integrated circuit.

15. The apparatus of claim 12, the first configuration of configurable laser light converter comprising:

a condenser lens optically coupled with the laser source;

an aperture stop optically coupled with the condenser lens;

a field stop optically coupled with the aperture stop; and

a field lens optically coupled with the field stop.

16. The apparatus of claim 15, the second configuration of configurable laser light converter comprising a collimating lens optically coupled with the laser source;

17. The apparatus of claim 16, wherein:

in the second configuration, the collimating lens is rotated into an optical path between the laser source and the beam splitter, and the condenser lens and the field lens are rotated out of the optical path between the laser source and the beam splitter;

in the first configuration, the collimating lens is rotated out of the optical path between the laser source and the beam splitter, and the condenser lens and the field lens are rotated into the optical path between the laser source and the beam splitter; and

wherein the aperture stop and the field stop each remain in a constant position in the optical path between the laser source and the beam splitter in both the first configuration and the second configuration.

18. The apparatus of claim 12, further comprising:

a fiber coupling lens optically coupled with the laser source;

a first end of an optical fiber optically coupled with the fiber coupling lens; and

a second end of the optical fiber optically coupled with the configurable laser light converter.

19. The apparatus of claim 12, further comprising a beam trap optically coupled with the beam splitter.

20. The apparatus of claim 12, the image sensor comprising at least one of a charge-coupled device camera, a focal plane array camera, and a CMOS camera.

21. The apparatus of claim 12, wherein light from the laser source is adapted in the first configuration to image an area of an integrated circuit optically coupled with the charged particle beam tool.

22. The apparatus of claim 12, wherein light from the laser source is adapted in the second configuration to heat an area of an integrated circuit optically coupled with the charged particle beam tool.

23. A charged particle beam tool comprising the apparatus of claim 12.

24. An apparatus for optically coupling a laser source to a dual-column charged particle beam tool, the apparatus comprising:

a beam splitter optically coupled with the laser source;

a quarter-waveplate optically coupled with the laser source;

a photo-detector optically coupled with the beam splitter;

a frame grabber electrically coupled with the photo-detector;

at least one scan mirror optically coupled with the beam splitter;

a scanning lens optically coupled with the at least one scan mirror and an objective lens;

at least one beam scanner configured to move the at least one scan mirror to alter an optical path of light from the laser source within the optical port; and

a scanning controller electrically coupled with the at least one beam scanner, the scanning controller configured to control the movement of the at least one scan mirror via the at least one beam scanner.

25. The apparatus of claim 24, the at least one scan mirror comprising a horizontal scan mirror optically coupled with a vertical scan mirror.

26. The apparatus of claim 24, further comprising a scanning lens optically coupled with the at least one scan mirror and the objective lens.

27. The apparatus of claim 26, further comprising an alignment mirror optically coupled with the scanning lens and the objective lens.

28. The apparatus of claim 27, further comprising a spatial filter optically coupled with the beam splitter and the photo-detector.

29. The apparatus of claim 28, the spatial filter comprising:

a collimation lens optically coupled with a fiber and the beam splitter;

the fiber optically coupled with the laser source;

a focusing lens optically coupled with the beam splitter and the photo-detector; and

a pinhole structure optically coupled with the focusing lens and the photo-detector.

30. The apparatus of claim 24, wherein the photo-detector is a photodiode or a photo multiplier.

31. The apparatus of claim 24, wherein the beam scanner is a galvanometric scanner, an acousto-optic scanner, or a rotating polygon.

32. The apparatus of claim 24, further comprising:

a fiber coupling lens optically-coupled with the laser source;

a first end of an optical fiber optically coupled with the fiber coupling lens; and

a collimating lens optically coupled with a second end of the optical fiber and the beam splitter.

33. The apparatus of claim 24, wherein light from the laser source is adapted to image an area of an integrated circuit optically coupled with the charged particle beam tool.

34. The apparatus of claim 24, wherein light from the laser source is adapted to heat an area of an integrated circuit optically coupled with the charged particle beam tool.

35. A charged particle beam tool comprising the apparatus of claim 24.

36. An apparatus for optically coupling a laser source and a whitelight source to a dual-column charged particle beam tool having an optical port, the apparatus comprising:

first means for directing light from the whitelight source through the optical port;

second means for directing light from the laser source through the optical port;

the light from the second light directing means being substantially parallel with the light from the first light directing means; and

means for capturing imaging light from the optical port, the imaging light being directed toward the capturing means by the first and second light directing means.

37. The apparatus of claim 36, further comprising means for controlling the intensity of the light from the whitelight source directed through the optical port by the first light directing means.

38. The apparatus of claim 36, further comprising means for adjusting an area illuminated by the light from the whitelight source directed through the optical port by the first light directing means.

39. The apparatus of claim 36, further comprising means for selecting a portion of the frequency spectrum of the light from the whitelight source directed through the optical port by the first light directing means.

40. An apparatus for optically coupling a laser source to a dual-column charged particle beam tool having an optical port, the apparatus comprising:

means for converting light from the laser source into a light beam of a selectable width;

means for directing the light beam from the converting means through the optical port; and

means for capturing imaging light from the optical port, the imaging light being directed toward the capturing means by the light directing means.

41. An apparatus for optically coupling a laser source to a dual-column charged particle beam tool having an optical port, the apparatus comprising:

means for scanning a light beam from the laser source through an area of the optical port;

means for capturing imaging light from the optical port; and

means for directing the imaging light from the optical port to the capturing means.

42. The apparatus of claim 41, further comprising means for forming an image from the imaging light captured by the capturing means.

43. The apparatus of claim 41, further comprising means for spatially filtering imaging light received by the capturing means.