X-ray inspection apparatus for inspecting semiconductor wafers

Patent metadata

Field	Value
Publication number	US-10215716-B2
Application number	US-201515104239-A
Country	US
Kind code	B2
Filing date	Apr 3, 2015
Priority date	Apr 4, 2014
Publication date	Feb 26, 2019
Grant date	Feb 26, 2019

Abstract

An x-ray inspection system includes a cabinet including an x-ray source, a sample support supporting a sample to be inspected, and an x-ray detector. The system further includes an air mover configured to force air into the cabinet through an air inlet in the cabinet above the sample support. The air mover and cabinet are configured to force air through the cabinet from the air inlet past the sample support to an air outlet in the cabinet below the sample support. The cabinet may be constructed to provide an x-ray shield. The x-ray inspection system can be used in a clean room environment to inspect items such as semiconductor wafers.

First claim

The invention claimed is:

1. An x-ray inspection system, comprising:
a cabinet comprising an x-ray source, a sample support supporting a sample to be inspected below the x-ray source, and an x-ray detector below the sample support and configured to measure attenuation of x-ray through the sample; and
an air mover configured to force air into the cabinet through an air inlet in the cabinet above the sample support, past the sample support, and to an air outlet in the cabinet below the x-ray detector,
wherein the air outlet comprises a shielding plate and a labyrinthine airflow path past the shielding plate to prevent the escape of the x-rays through the air outlet.

2. The x-ray inspection system according to claim 1 , wherein the cabinet prevents x-rays from the x-ray source from escaping from the cabinet.

3. The x-ray inspection system according claim 1 , wherein the air mover comprises an x-ray shield arranged to prevent the escape of the x-rays from the cabinet through the air mover.

4. The x-ray inspection system according claim 1 , further comprising a HEPA or ULPA air filter, the air filter being located above the sample support.

5. The x-ray inspection system according to claim 4 , wherein the air filter is coupled to the air mover.

6. The x-ray inspection system according to claim 3 , wherein the x-ray shield is a baffle plate coupled to the air mover.

7. The x-ray inspection system according to claim 1 , wherein the x-ray source is fixed relative to the cabinet.

8. The x-ray inspection system according to claim 1 , wherein the x-ray source is a sealed x-ray tube with a transmission target.

9. The x-ray inspection system according to claim 1 , further comprising a first positioning assembly that allows for relative movement between the sample support and the x-ray source, wherein the first positioning assembly is located below the sample support.

10. The x-ray inspection system according to claim 9 , further comprising a second positioning assembly that allows for movement between the x-ray detector and the x-ray source, wherein the second positioning assembly is located below the sample support.

11. The x-ray inspection system according to claim 10 , further comprising a perforated deck positioned below the x-ray source and above the first and second positioning assemblies, wherein the perforated deck and air mover are configured to provide a first air pressure above the perforated deck and a second air pressure below the perforated deck, and wherein the second air pressure is lower than the first air pressure.

12. The x-ray inspection system according to claim 1 , wherein the sample is a semiconductor wafer.

13. A method of inspecting a semiconductor wafer, the method comprising:
directing x-rays at a semiconductor wafer originating from above the semiconductor wafer;
detecting x-rays that have passed through the semiconductor wafer using an x-ray detector below the semiconductor wafer; and
directing a laminar airflow from above the semiconductor wafer, past the semiconductor wafer, and to an air outlet past a shielding plate and through a labyrinthine airflow path below the semiconductor wafer simultaneously with the steps of directing and detecting.

14. The x-ray inspection system according to claim 1 , wherein the air outlet is positioned at the center of the cabinet to cause laminar flow of the air through the cabinet.

15. The x-ray inspection system according to claim 9 , further comprising a proximity sensor configured to detect a distance between a top surface of the sample and the x-ray source.

16. The x-ray inspection system according to claim 15 , further comprising a controller configured to receive the distance between a top surface of the sample and the x-ray source, and to calibrate the first positioning assembly based on the received distance.

17. The x-ray inspection system according to claim 15 , further comprising a perforated deck positioned at the same height as an uppermost position of the sample support.

18. The x-ray inspection system according to claim 1 , wherein the sample support comprises a plurality of depressions, and the system further comprises a vacuum configured to creates low pressure in the depressions underneath the sample to hold the sample against the sample support.

19. An x-ray inspection system, comprising:
a cabinet comprising an x-ray source, a sample support supporting a semiconductor wafer to be inspected below the x-ray source, and an x-ray detector below the sample support and configured to measure attenuation of x-ray through the semiconductor wafer;
a first positioning assembly that allows for relative movement between the sample support and the x-ray source;
a second positioning assembly that allows for movement between the x-ray detector and the x-ray source;
a perforated deck positioned below the x-ray source and above the x-ray detector; and
an air mover configured to force air into the cabinet through an air inlet in the cabinet above the sample support, past the sample support, and to an air outlet in the cabinet below the x-ray detector,
wherein the perforated deck and air mover are configured to provide a first air pressure above the perforated deck and a second air pressure below the perforated deck, and wherein the second air pressure is lower than the first air pressure.

Assignees

• Nordson Corp

Inventors

• Tingay John
• Walker William T
• Donaldson-Stewart Kate

Classifications

• H10P74/203

  Structural properties, e.g. testing or measuring thicknesses, line widths, warpage, bond strengths or physical defects · CPC title

• H10P72/0616

  Monitoring of warpages, curvatures, damages, defects or the like · CPC title

• H10P72/78

  using vacuum or suction, e.g. Bernoulli chucks · CPC title

• H10P72/53

  using optical controlling means · CPC title

• G01N2223/6116

  semiconductor wafer · CPC title