Imaging semiconductor structures using solid state illumination

• US 20050231713A1
• Filed: 04/19/2005
• Published: 10/20/2005
• Est. Priority Date: 04/19/2004
• Status: Active Grant

• Current Assignee: Viscom AG (HPC Vermögensverwaltung GmbH)
• Original Assignee: Viscom AG (HPC Vermögensverwaltung GmbH)
• Inventors: Olson, Steven J., Owen, Mark D., Vlach, Francois
• Granted Patent: US 8,077,305 B2
• Time in Patent Office: Days
• US Class Current: 356/237.100
• 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 through-substrate optical inspection system for inspecting semiconductor structure, comprising a solid state radiation source oriented to provide backlight with radiation at a first wavelength having intensity >

0.001 mW/cm2, a second solid state radiation source oriented to provide toplight with radiation at a second wavelength having intensity >

0.001 mW/cm2, and a solid state imaging device sensitive to the first and second wavelengths, and wherein the second solid state radiation source provides radiation at wavelengths, times and intensity insufficient to saturate the imaging device, whereby the imaging device may capture inspection information from the first solid state radiation source.

2. An inspection system as in claim 1, wherein the first radiation source provides radiation at one or more wavelengths that are transmissive of the semiconductor structure.

3. An inspection system as in claim 1, wherein at least one light source comprises one or more arrays of light-emitting, solid state semiconductor devices.

4. An inspection system as in claim 3, wherein the an array of light-emitting, solid state semiconductor devices provides radiation at one or more wavelengths that are transmissive of the semiconductor structure.

5. An inspection system as in claim 1, wherein the semiconductor structure is silicon-based and the first radiation source provides radiation at wavelengths in a range of 1050-1200 nm.

6. An inspection system as in claim 5, wherein the semiconductor structure is silicon-based and the second radiation source provides radiation at wavelengths in a range of 1100-1300 nm.

7. An inspection system as in claim 1, further comprising a lens system that provides resolution matched to the resolution of the imaging device.

8. An inspection system as in claim 7, wherein the imaging device has useful spectral sensitivity up to wavelengths at least as long as 1200 nm and has sensor cell size with dimensions at or below half the dimension of the semiconductor structure'"'"'s relevant feature.

9. An inspection system as in claim 8, further comprising a plurality of lighting systems to support a selected combination of front side, backside, side and dark field irradiation of the semiconductor structure.

10. An inspection system as in claim 1, further comprising an image processing mechanism, which mechanism supports at least one of stretching the region of interest, identifying edges and features in the image, and automatically inspecting the semiconductor structure.

11. An inspection system as in claim 10, wherein the image processing mechanism provides for measuring height of a feature enclosed between two silicon wafers of the semiconductor structure.

12. An inspection system as in claim 1, wherein the semiconductor structure includes direct fusion bonded semiconductor materials and at least one of the radiation sources provide radiation at orientation, wavelength and intensity sufficient to enable detection of the presence of defects associated with the bond of such structure.

13. An inspection system as in claim 1, wherein the imaging device captures an image of at least one alignment target associated with the semiconductor structure.

14. An inspection system as in claim 1, wherein the imaging device captures an image representative of crystal defects—

cracks, insertions or voids—

inside the semiconductor structure.

15. An inspection system as in claim 1, wherein the imaging device captures 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.

16. A process for an inspection system, the process providing for inspection of a semiconductor structure for relevant features, such features having known size, the process comprising:

identifying the semiconductor structure'"'"'s relevant semiconductor materials and associated band-gap energy or energies,

identifying the semiconductor structure'"'"'s relevant features, including size and location of such features;

selecting one or more imaging devices based on the resolution thereof, in coordination with the size of the relevant features;

identifying the imaging device'"'"'s spectral sensitivity curve;

determining one or more orientations for irradiation using one or more radiation sources, in coordination with the location of such features;

selecting one or more radiation wavelength(s) or band(s) of wavelength(s) based on such materials, energies, size and location, in coordination with orientation of the radiation sources and the spectral sensitivity curve of the imaging device; and

selecting one or more solid state radiation sources to provide the one or more selected radiation wavelengths at the selected orientations.

17. A process for an inspection system as in claim 16, further comprising selecting a lens system so as to transmit the selected wavelengths to, and form the images on, the imaging device which selection matches the lens'"'"' image-forming capabilities with the imaging device'"'"'s image-capture capabilities.

18. A process for an inspection system as in claim 16, further comprising operating the selected one or more solid state radiation sources to control radiation characteristics, including as to one or more of intensity, collimation, lack of collimation, and pulsed operation.

19. A process for an inspection system as in claim 16, further comprising operating the selected one or more solid state radiation sources so that, when imaging using wavelengths transmissive of the structure, other wavelengths are substantially excluded, whereby the imaging device images the structure responsive to the selected, transmissive wavelengths.

20. A process for an inspection system as in claim 16, wherein selecting 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.