METHOD OF MEASURING CRITICAL DIMENSION OF PATTERN AND APPARATUS FOR PERFORMING THE SAME

• US 20120105617A1
• Filed: 09/20/2011
• Published: 05/03/2012
• Est. Priority Date: 11/02/2010
• Status: Active Grant

• Current Assignee: Samsung Electronics Co. Ltd.
• Original Assignee: Samsung Electronics Co. Ltd.
• Inventors: YOON, Han-June, Lee, Hyung-Joo, Park, Won-Joo
• Granted Patent: US 8,988,521 B2
• Time in Patent Office: Days
• US Class Current: 348/80
• CPC Class Codes: G06T 2207/10061 from scanning electron microscope
• CPC Class Codes: G06T 2207/30148 Semiconductor; IC; Wafer
• CPC Class Codes: G06T 7/001 using an image reference approach
• CPC Class Codes: G06T 7/11 Region-based segmentation
• CPC Class Codes: G06T 7/60 Analysis of geometric attributes

Abstract

In a method of measuring a critical dimension of a pattern, a pattern image is obtained from an object pattern. A design pattern of the object pattern and the pattern image are matched to determine a detection region on the pattern image. An optimum turning point of the pattern contour is determined in the detection region and a ROI (region of interest) is set within a predetermined range from the optimum turning point. A critical dimension of the pattern is measured in the ROI.

Claims

1. A method of measuring a critical dimension of a pattern, the method comprising:

obtaining a pattern image from an object pattern;

matching a design pattern of the object pattern and the pattern image to determine a detection region on the pattern image;

determining an optimum turning point of the pattern contour in the detection region; and

setting a ROI (region of interest) within a predetermined range from the optimum turning point; and

measuring a critical dimension of the pattern in the ROI.

2. The method as claimed in claim 1, wherein determining the detection region comprises:

obtaining a corresponding relation between the contour of the design pattern and the pattern contour using design data of the design pattern; and

determining the detection region including expected single points or regions of the pattern contour on the pattern image based on the corresponding relation.

3. The method as claimed in claim 1, wherein determining the optimum turning point of the pattern contour comprises:

obtaining coordinates at predetermined intervals along the contour of the pattern within the detection region; and

determining a single point of the coordinates as the optimum turning point.

4. The method as claimed in claim 3, wherein determining a single point of the coordinates as the optimum turning point includes determining a respective one of the coordinates at which a tangent line of the pattern contour changes and/or the pattern contour has an unusual behavior compared to other coordinates as the optimum turning point.

5. The method as claimed in claim 4, wherein determining a single point of the coordinates as the optimum turning point includes determining, as the optimum turning point, a respective one of the coordinates at which the tangent line of the pattern contour changes at least by a predetermined amount.

6. The method as claimed in claim 1, wherein setting the ROI comprises:

calculating a center of the ROI using the optimum turning point; and

determining a width of the ROI that is offset by a predetermined distance from the optimum turning point.

7. The method as claimed in claim 1, wherein measuring the critical dimension of the pattern in the ROI comprises:

obtaining coordinates of the pattern contour in the ROI; and

calculating an average of the coordinates of the pattern contour.

8. The method as claimed in claim 1, wherein obtaining a pattern image comprises:

irradiating and scanning primary electrons on the pattern; and

detecting secondary electrons from the pattern to obtain the pattern image.

9. An apparatus for measuring a critical dimension of a pattern, the apparatus comprising:

a contour detecting portion configured to detect a pattern contour from a pattern image of an object pattern;

a matching portion configured to match a design pattern of the object pattern and the pattern image to determine a detection region on the pattern image;

a ROI determination portion configured to determine an optimum turning point of the pattern contour in the detection region and set a ROI (region of interest) within a predetermined range from the optimum turning point; and

a measuring portion configured to measure a critical dimension of the pattern in the ROI.

10. The apparatus as claimed in claim 9, wherein the matching portion is configured to obtain a corresponding relation between the contour of the design pattern and the pattern contour using design data of the design pattern and to determine the detection region, including expected single points or regions of the pattern contour, on the pattern image based on the corresponding relation.

11. The apparatus as claimed in claim 9, wherein the ROI determination portion is configured to obtain coordinates at predetermined intervals along the contour of the pattern within the detection region and to determine a single point of the coordinates as the optimum turning point.

12. The apparatus as claimed in claim 9, wherein the ROI determination portion is configured to calculate a center of the ROI using the optimum turning point and to determine a width of the ROI that is offset by a predetermined distance from the optimum turning point.

13. The apparatus as claimed in claim 9, wherein the measuring portion is configured to obtain coordinates of the pattern contour in the ROI and to calculate an average of the coordinates of the pattern contour.

14. An apparatus for measuring a critical dimension of an object pattern using a pattern image of the object pattern, the pattern image including a boundary of the object pattern, the apparatus comprising:

a region-of-interest (ROI) determinator configured to determine at least one optimum reference point along the boundary of the pattern image in a detected region of the object pattern and set a ROI within a predetermined range from the optimum reference point; and

a measuring unit configured to measure a critical dimension of a portion of the pattern in the ROI.

15. The apparatus as claimed in claim 14, further comprising:

a pattern matcher configured to align a design pattern of the object pattern and the pattern image to determine the detected region of the pattern image.

16. The apparatus as claimed in claim 15, wherein the pattern matcher determines a plurality of reference points and/or regions along the boundary of the pattern image in the detected region surrounding a portion of the pattern to be measured by the measuring unit.

17. The apparatus as claimed in claim 16, wherein the plurality of reference points are determined by sampling every x-th pixel along the boundary of the pattern, where x is an integer equal to or greater than one.

18. The apparatus as claimed in claim 16, wherein the ROI determinator is configured to determine at least one optimum reference point among the plurality of reference points and/or regions along the boundary of the pattern image to set a ROI region at a predetermined distance from the at least one optimum reference point.

19. The apparatus as claimed in claim 18, wherein the ROI determinator is configured to determine the at least one optimum reference point from among the plurality of reference points based on characteristics of tangent lines tangent to the respective points along the boundary of the pattern.

20. The apparatus as claimed in claim 19, wherein the ROI determinator is configured to determine a plurality of optimum reference points including an upper optimum reference point and a lower optimum reference point along a single direction and to set the ROI to be a predetermined distance from each of the upper optimum reference point and the lower optimum reference point.