Imaging semiconductor structures using solid state illumination

• US 8,077,305 B2
• Filed: 04/19/2005
• Issued: 12/13/2011
• Est. Priority Date: 04/19/2004
• Status: Active Grant

• Current Assignee: Viscom AG (HPC Vermögensverwaltung GmbH)
• Original Assignee: Viscom AG (HPC Vermögensverwaltung GmbH)
• Inventors: Owen, Mark D., Vlach, Francois, Olson, Steven J.
• Primary Examiner(s): Toatley, Gregory J
• Assistant Examiner(s): VALENTIN II, JUAN D
• Application Number:
  US11/109,903
• Publication Number:
  US 20050231713A1
• Time in Patent Office: 2,429 Days
• Field of Search: 3562372-2375
• US Class Current: 356/237.1
• CPC Class Codes: G01N 21/8806 Specially adapted optical and illumination features
• CPC Class Codes: G01N 21/9505 Wafer internal defects, e.g. microcracks
• 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

Abstract

The invention consists of a camera, light sources, lenses and software algorithms that are used to image and inspect semiconductor structures, including through infrared radiation. The use of various configurations of solid state lighting and software algorithms enhances the imaging and inspection.

Claims

1. A system for imaging subsurface features of a target object comprising a semiconductor-based material having first and second surfaces, and a subsurface therebetween, the system comprising:

a solid-state sensor having an array of pixels and a sufficient quantum efficiency for wavelengths between about 750 nm and about 3000 nm to image subsurface structures or structure features in the semiconductor material illuminated by radiation wavelength between about 750 nm and about 3000 nm, when a portion of the radiation that illuminated the subsurface is incident on the image sensor; and

a solid-state radiation source operable with a radiation output in the aforesaid wavelength range, wherein the radiation source and the image sensor are arranged in the system so that the output radiation penetrates through material forming the first and/or second surface and into underlying subsurface material, and is thereafter directed to the sensor.

2. A system as in claim 1, wherein the solid state radiation source comprises one or more high-density arrays of light-emitting diodes, such an array providing for control over and selected variations of, one or more of (i) collimation of a selected first and/or second wavelength and/or (ii) intensity and/or (iii) duty cycle.

3. A system as in claim 2, wherein one or more of the high-density arrays of light-emitting diodes is controllable as to collimation of radiation and disposed relative to the work object so as to provide for selected incident angle of the radiation.

4. A system as in claim 1, further comprising selected one or more additional radiation sources, so as to support a selected combination of front side, backside, side and/or dark field irradiation of the work object.

5. A system as in claim 1, further comprising an image processing mechanism, which mechanism supports one or more of stretching the region of interest, identifying edges and features in the image, and automatically inspecting the target object.

6. A system as in claim 5, wherein the image processing mechanism provides for measuring height of a semiconductor structure or feature disposed between two layers of semiconductor materials.

7. A system as in claim 1, wherein the first solid state radiation source provides radiation at a selected combination of orientation, collimation, wavelength, duty cycle, coherence and intensity sufficient to enable detection of defects associated with a target object that includes direct fusion bonded semiconductor materials.

8. A system as in claim 1, wherein the imaging device captures an image of semiconductor structure that comprises at least one alignment target.

9. A system as in claim 1, wherein the imaging system provides for capturing an image representing the depth or z location of a buried defect, like a crack, dislocation or void, whereby such depth or z location is measured.

10. The system of claim 1 wherein the radiation source and image sensor are arranged to allow placement of the target object between the radiation source and the image sensor so that light passes directly through the target object to reach the sensor.

11. The system of claim 10 wherein the light source is operable to output a wavelength range comprising about 1050 nm to about 1300 nm.

12. The system of claim 1 wherein the radiation source is disposed so as to allow placement of the radiation source on the same side of the target object as the image sensor so that radiation passes through the target object and is reflected back to the sensor, again through the target object.

13. The system of claim 12 wherein the light source is operable to output a wavelength range comprising about 1050 nm to about 1300 nm.

14. The system of claim 12 wherein one of the first or second surfaces comprises a reflective material that reflects the radiation penetrating the subsurface back through the subsurface to the image sensor.

15. The system of claim 1 wherein the light source is operable to output a wavelength range comprising about 1050 nm to about 1300 nm.

16. The system of claim 1 wherein the light source is operable to output radiation of at least two different wavelengths within the range.

17. The system of claim 1 wherein the system provides for imaging a silicon-based semiconductor material.

18. The system of claim 1 wherein the target object comprises a semiconductor device with subsurface semiconductor structures having features to be imaged.

19. The system of claim 1 wherein the subsurface includes a structure comprising the semiconductor material to be imaged.

20. A process for an inspection system as in claim 19, further comprising operating the solid state radiation source so that, when imaging using wavelengths transmissive of the semiconductor material, other wavelengths are substantially excluded, whereby the image sensor images the target object responsive to the selected, transmissive wavelengths.

21. The system of claim 1 wherein the subsurface comprises two or more layers of semiconductor materials to be imaged for structures or features.

22. A system as in claim 1, further comprising a second solid state radiation source and wherein at least one of the first or second solid state radiation sources provides radiation at a selected combination of orientation, collimation, wavelength, duty cycle, coherence and intensity sufficient to enable detection of defects associated with a target object that includes direct fusion bonded semiconductor materials.

23. A system as in claim 1, wherein the solid-state radiation source comprises one or more high-density arrays of light-emitting diodes configured to vary a collimation of a selected wavelength of radiation.

24. A process for imaging a target object comprising a semiconductor-based material having first and second surfaces, and a subsurface therebetween, the process comprising:

providing a solid-state sensor having an array of pixels and a sufficient quantum efficiency for wavelengths between about 750 nm and about 3000 nm to image subsurface structures or structure features in the semiconductor material illuminated by a radiation wavelength between about 750 nm and about 3000 nm, when a portion of the radiation that illuminated the subsurface is incident on the image sensor; and

providing a solid-state radiation source operable with a radiation output in the aforesaid wavelength range; and

arranging the radiation source and the image sensor in the system so that the output radiation penetrates through material forming the first and/or second surface and into underlying subsurface material, and is thereafter directed to the sensor.

25. The process of claim 24 further comprising providing for capturing an image representative of subsurface semiconductor structure features that comprise crystal defects, cracks, insertions or voids.

26. A process for an inspection system as in claim 24, wherein the radiation source comprises one or more high-density arrays of light-emitting diodes, such one or more arrays providing for control over and selected variations of, one or a combination of two or all of, (i) collimation of the selected first and/or second radiation wavelengths and/or (ii) intensity and/or (iii) duty cycle.

27. A process for an inspection system as in claim 24, further comprising operating the system using one or more radiation wavelength(s) or band(s) of wavelength(s) provides wavelength(s) that are both long enough to be transmitted entirely through the structure and short enough to enable imaging of the features.

28. The process of claim 24 further comprising placing the target object into the system so that it is arranged for radiation to pass through it to the image sensor, in the manner said, and outputting radiation so that it penetrates through the first and/or second surface and into the subsurface and is then directed to the sensor.

29. The process of claim 28 wherein the target object comprises a MEMs device, and further comprising the step of operating the radiation source and image sensor to inspect the device for defects.

30. The process of claim 28 wherein the target object comprises one or more bonded layers, and further comprising the step of operating the radiation source and image sensor to inspect the target object, assessing for defects at a bond layer interface.

31. The process of claim 24 wherein the radiation source and image sensor are arranged to allow placement of the target object between the radiation source and the image sensor so that light passes directly through the subsurface to reach the sensor.

32. The process of claim 31 wherein the light source is operable to output a wavelength range comprising about 1050 nm to about 1300 nm.

33. The process of claim 24 wherein the radiation source is disposed so as to allow placement of the radiation source on about the same side of the target object as the image sensor so that radiation penetrates through the subsurface and is reflected back to the sensor, again through the subsurface.

34. The process of claim 33 wherein the light source is operable to output a wavelength range comprising about 1050 nm to about 1300 nm.

35. The process of claim 33 wherein one of the first or second surfaces comprises a reflective material that reflects the radiation penetrating the subsurface back through the subsurface to the image sensor.

36. The process of claim 35 wherein the target object comprises a semiconductor device and a metallic layer in the device comprises the reflective material.

37. The process of claim 24 wherein the light source is operable to output a wavelength range comprising about 1050 nm to about 1300 nm.

38. A process as in claim 24, wherein the solid-state radiation source comprises one or more high-density arrays of light-emitting diodes configured to vary a collimation of a selected wavelength of radiation.