Method and apparatus for analyzing a defective location of a photolithographic mask

Patent metadata

Field	Value
Publication number	US-11150552-B2
Application number	US-201916563303-A
Country	US
Kind code	B2
Filing date	Sep 6, 2019
Priority date	Mar 9, 2017
Publication date	Oct 19, 2021
Grant date	Oct 19, 2021

Abstract

The present invention relates to a method for analyzing at least one defective location of a photolithographic mask, having the following steps: (a) obtaining measurement data for the at least one defective location of the photolithographic mask; (b) determining reference data of the defective location from computer-aided design (CAD) data for the photolithographic mask; (c) correcting the reference data with at least one location-dependent correction value; and (d) analyzing the defective location by comparing the measurement data to the corrected reference data.

First claim

What is claimed is:

1. A method for analyzing at least one defective location of a photolithographic mask, wherein the method comprises the following steps:
a. obtaining measurement data for the at least one defective location of the photolithographic mask;
b. determining reference data of the defective location from computer-aided design (CAD) data for the photolithographic mask;
c. correcting the reference data with at least one location-dependent correction value; and
d. analyzing the defective location by comparing the measurement data to the corrected reference data.

2. The method of claim 1 , wherein obtaining measurement data for the at least one defective location of the photolithographic mask comprises: scanning the at least one defective location with a particle beam.

3. The method of claim 1 , furthermore comprising the step of: producing a measurement data image from the measurement data.

4. The method of claim 3 , further including the step of: determining the at least one location-dependent correction value by minimizing the difference between the CD of the structure elements of the measurement data image and the CD of the structure elements of the reference image for each of the at least one defective location of the photolithographic mask.

5. The method of claim 4 , wherein minimizing the difference between the CD of the structure elements of the measurement data image and the CD of the structure elements of the reference image is effected in a region of the photolithographic mask around the at least one defective location, wherein the region excludes the at least one defective location, and wherein the region is larger than the at least one defective location.

6. The method of claim 5 , wherein minimizing the difference between the CD of the structure elements of the measurement data image and the CD of the structure elements of the reference image comprises: determining the parameters of the point spread function in the region around the at least one defective location, with the result that the difference between the CD of the structure elements of the measurement data image and of the reference image becomes minimal.

7. The method of claim 4 , wherein determining the at least one location-dependent correction value comprises: performing an algorithm that minimizes the difference between the CD of the structure elements of the measurement data image and the CD of the structure elements of the reference image.

8. The method of claim 4 , further including the step of: determining a distribution of the CD of at least one pattern element and/or a mark over the photolithographic mask.

9. The method of claim 8 , furthermore including the step of: determining at least one location-dependent correction value from the distribution of the CD of the at least one pattern element and/or the mark, and producing a corrected reference image with the aid of the produced distribution of the CD.

10. The method of claim 1 , wherein determining reference data comprises: extracting a section from the CAD data which comprises the at least one defective location of the photolithographic mask.

11. The method of claim 1 , wherein determining reference data comprises: synthesizing a reference image from the CAD data.

12. The method of claim 11 , wherein synthesizing the reference image furthermore comprises: producing a light boundary for at least one structure element in the reference image.

13. The method of claim 12 , wherein the at least one structure element comprises an element from the following: a pattern element of the photolithographic mask, a mark of the photolithographic mask, and a defect of the at least one defective location of the photolithographic mask.

14. The method of claim 11 , wherein synthesizing the reference image furthermore comprises: determining parameters of a point spread function that describes an exposure process for the photolithographic mask during a mask production process.

15. The method of claim 11 , wherein the at least one location-dependent correction value takes into account a difference between a critical dimension (CD) of the measurement data and the CAD data at the defective location.

16. The method of claim 11 , wherein correcting the reference data comprises: forming a corrected reference image by correcting the reference image with the at least one location-dependent correction value.

17. The method of claim 1 , wherein synthesizing the reference image comprises: taking into account in the reference image systematic changes that CAD data undergo during a mask production process.

18. The method of claim 1 , wherein analyzing the at least one defective location comprises: determining a contour for the at least one defect of the at least one defective location.

19. The method of claim 18 , wherein determining the contour comprises: superposing the corrected reference data of the defective location and the measurement data of the defective location, and identifying differences between the superposed corrected reference data and the measurement data.

20. A method for analyzing at least one defective location of a photolithographic mask, wherein the method comprises the following steps:
a. obtaining measurement data for the at least one defective location of the photolithographic mask;
b. determining reference data of the defective location from computer-aided design (CAD) data for the photolithographic mask;
c. determining a contour of the at least one defective location from the measurement data and the reference data; and
d. analyzing the defective location by correcting the contour of the at least one defective location with at least one location-dependent correction value.

21. The method of claim 20 , wherein determining the contour comprises: superposing the reference data of the defective location and the measurement data of the defective location, and identifying differences between the superposed reference data and the measurement data.

22. A non-transitory computer program comprising instructions which, when executed by a computer system, prompt the computer system to carry out the method steps of claim 1 .

23. An apparatus for analyzing at least one defective location of a photolithographic mask, including:
a. means for obtaining measurement data for the at least one defective location of the photolithographic mask;
b. means for determining reference data of the defective location from computer-aided design (CAD) data for the photolithographic mask;
c. means for correcting the reference data with at least one location-dependent correction value; and
d. means for analyzing the defective location by comparing the measurement data to the corrected reference data.

24. An apparatus for analyzing at least one defective location of a photolithographic mask, including:
a. means for obtaining measurement data for the at least one defective location of the photolithographic mask;
b. means for determining reference data of the defective location from computer-aided design (CAD) data for the photolithographic mask;
c. means for determining a contour of the at least one defective location from the measurement data and the reference data; and
d. analyzing the defective location by correcting the contour with at least one location-dependent correction value.

Assignees

• Zeiss Carl Smt Gmbh

Inventors

• Budach Michael
• Schönberger Ralf

Classifications

• G03F7/706837

  Data analysis, e.g. filtering, weighting, flyer removal, fingerprints or root cause analysis · CPC title

• G03F1/84 Primary

  Inspecting · CPC title

• G06T7/001

  using an image reference approach · CPC title

• G06T2207/30148

  Semiconductor; IC; Wafer · CPC title

• G03F7/705

  Modelling or simulating from physical phenomena up to complete wafer processes or whole workflow in wafer productions · CPC title