Inspection apparatus and method

Patent metadata

Field	Value
Publication number	US-12072181-B2
Application number	US-202117487896-A
Country	US
Kind code	B2
Filing date	Sep 28, 2021
Priority date	Oct 1, 2020
Publication date	Aug 27, 2024
Grant date	Aug 27, 2024

Abstract

An inspection apparatus for adjusting a working height for a substrate for multiple target heights is disclosed. The inspection apparatus includes a radiation source configured to provide a radiation beam and a beam splitter configured to split the radiation beam into multiple beamlets that each reflect off a substrate. Each beamlet contains light of multiple wavelengths. The inspection apparatus includes multiple light reflecting components, wherein each light reflecting component is associated with one of the beamlets reflecting off the substrate and is configured to support a different target height for the substrate by detecting a height or a levelness of the substrate based on the beamlet reflecting off the substrate.

First claim

The invention claimed is:

1. An inspection apparatus comprising:
a beam splitter configured to split a radiation beam into multiple beamlets that each reflect off a substrate; and
multiple radiation reflecting components, wherein each radiation reflecting component is associated with one of the beamlets and is configured to support a different target height for the substrate by enabling detection of a height or a levelness of the substrate based on the associated beamlet reflecting off the substrate,
wherein the beam splitter is configured to provide one of the beamlets at a different incidence angle on the substrate than another one of the beamlets and/or the multiple radiation reflecting components are arranged to provide the beamlets on the substrate and such that one of the radiation reflecting components is oriented at a different angle than another one of the radiation reflecting components.

2. The inspection apparatus of claim 1 , further comprising a detector configured to detect multiple images of a pattern projected on the substrate by receiving the beamlets from the radiation reflecting components, wherein each image is formed by a different beamlet.

3. The inspection apparatus of claim 2 , further comprising controller circuitry configured to:
compare a first image of the images with a reference image corresponding to a first target height of the different target heights, and
determine a first deviation value for the substrate from the first target height based on the comparison.

4. The inspection apparatus of claim 3 , wherein the first image is formed by one of the beamlets associated with one of the radiation reflecting components, and wherein the one of the radiation reflecting components is configured to enable measurement of the first deviation value of the substrate for the first target height.

5. The inspection apparatus of claim 3 , further comprising a stage motion controller having circuitry configured to adjust a height of a stage that is configured to hold the substrate to position the substrate at the first target height, wherein the height of the stage is adjusted based on the first deviation value.

6. The inspection apparatus of claim 3 , further comprising a beam controller to adjust a focus of a charged-particle beam incident on the substrate to compensate, at least in part, for the first deviation value.

7. The inspection apparatus of claim 3 , wherein the controller circuitry is configured to compare the first image with the reference image by:
generating the first image as a radiation intensity image of the pattern, and
conducting a cross-correlation between the radiation intensity image and the reference image to determine the first deviation value.

8. The inspection apparatus of claim 3 , wherein the reference image is obtained by projecting the pattern on a surface of a reference substrate.

9. The inspection apparatus of claim 1 , further comprising a radiation source configured to provide a broadband or a narrowband radiation.

10. The inspection apparatus of claim 1 , further comprising a radiation source configured to merge radiation from multiple narrowband sources to form a broadband radiation, and wherein each beamlet contains radiation of multiple wavelengths.

11. The inspection apparatus of claim 10 , wherein the radiation of multiple wavelengths facilitates minimizing an error in detection of height caused due to a variation of a material of the substrate.

12. The inspection apparatus of claim 1 , further comprising a prism to merge radiation from multiple narrowband sources.

13. The inspection apparatus of claim 1 , further comprising a plurality of dichromic mirrors to merge radiation from multiple narrow band sources.

14. The inspection apparatus of claim 1 , further comprising a beam splitter that includes a set of radiation splitting components, wherein the set of radiation splitting components are configured with different ratios of reflection to transmission to direct each of the beamlets on the substrate with the same energy.

15. A non-transitory computer-readable medium having instructions therein, the instructions, when executed by a computer system, configured to cause the computer system to at least:
obtain multiple images of a pattern generated by receipt by a level sensor of an inspection system of a plurality of beamlets that reflect off a substrate, wherein each image is formed by a different beamlet and supports measurement of a deviation value of the substrate from a different target height; and
determine a first deviation value of the substrate from a first target height based on a first image of the images that supports measurement of the deviation value of the substrate from the first target height and a second deviation value of the substrate from a second target height different from the first target height based on a second image of the images that supports measurement of the deviation value of the substrate from the second target height.

16. The medium of claim 15 , wherein the instructions are further configured to compare the first image with a reference image by:
generation of the first image as a radiation intensity image of the pattern, and
conducting of a cross-correlation between the radiation intensity image and the reference image to determine the first deviation value.

17. The medium of claim 15 , wherein the instructions are further configured to cause adjustment of a height of a stage that is configured to hold the substrate to position the substrate at the first target height, wherein the height of the stage is adjusted based on the first deviation value.

18. The medium of claim 15 , wherein the instructions are further configured to cause adjustment of a focus of a charged-particle beam incident on the substrate to compensate, at least in part, for the first deviation value.

19. The medium of claim 15 , wherein the instructions are further configured to:
compare the first image with a reference image corresponding to the first target height, and
determine the first deviation value for the substrate from the first target height based on the comparison.

20. An inspection apparatus comprising:
multiple radiation reflecting components, wherein each radiation reflecting component is associated with one beamlet of a plurality of beamlets, is configured to provide a respective beamlet on a the substrate, and is configured to support a different target height for a substrate by enabling detection of a height or a levelness of the substrate based on the associated beamlet reflecting off the substrate; and
a non-transitory computer-readable medium having instructions therein, the instructions, when executed by one or more processors, configured to cause the one or more processors to at least determine a first height or first deviation value from a target height using a first radiation reflecting component of the multiple radiation reflecting components but not a second radiation reflecting component of the multiple radiation reflecting components and determine a second height or second deviation value from a target height using the second radiation reflecting component of the multiple radiation reflecting components but not the first radiation reflecting component of the multiple radiation reflecting components.

Assignees

• Asml Netherlands Bv

Inventors

• Wang Yan
• Zhang Jian
• Kang Zhiwen
• Wang Yixiang

Classifications

• H01J2237/2814

  Measurement of surface topography · CPC title

• H01J2237/20235

  Z movement or adjustment · CPC title

• H01J37/28 Primary

  with scanning beams {(H01J37/268, H01J37/292, H01J37/2955 take precedence)} · CPC title

• H01J37/222

  Image processing arrangements associated with the tube · CPC title

• H01J37/21

  Means for adjusting the focus · CPC title