SCANNING ELECTRON MICROSCOPE

• US 20120298865A1
• Filed: 01/21/2011
• Published: 11/29/2012
• Est. Priority Date: 01/25/2010
• Status: Active Grant

• Current Assignee: Hitachi High-Tech Company Limited (Hitachi, Ltd.)
• Original Assignee: Hitachi High-Technologies Corporation (Hitachi, Ltd.)
• Inventors: Tanaka, Junichi, Nakayama, Yoshinori, Hitomi, Keiichiro, Omori, Seiko
• Granted Patent: US 9,110,384 B2
• Time in Patent Office: Days
• US Class Current: 250/310
• CPC Class Codes: G03F 7/70625 Dimensions, e.g. line width, critical dimension [CD], profile, sidewall angle or edge roughness
• CPC Class Codes: H01J 2237/1536 Image distortions due to scanning
• CPC Class Codes: H01J 2237/226 Image reconstruction
• CPC Class Codes: H01J 2237/24571 Measurements of non-electric or non-magnetic variables
• CPC Class Codes: H01J 2237/2809 characterised by the imaging problems involved
• CPC Class Codes: H01J 2237/2817 Pattern inspection
• CPC Class Codes: H01J 37/222 Image processing arrangements associated with the tube
• CPC Class Codes: H01J 37/28 with scanning beams H01J37/268, H01J37/292, H01J37/2955 take precedence

Abstract

Disclosed is a scanning electron microscope provided with a calculation device (403) for measuring the dimension of a pattern on a sample (413), characterized in that the amount of change of a pattern shape, caused by electron beam irradiation, is calculated and stored, and a pattern shape contour (614; 815; 1512) before the sample is irradiated with an electron beam is restored from a pattern shape contour (613; 814; 1511) in a scanning electron microscope image (612; 813; 1510) after the sample is irradiated with an electron beam using the calculated amount and, then, the pattern shape contour (614; 815; 1512) is displayed. Thus, the shrinking of a resist and/or the effect of electrostatic charge caused when a sample is irradiated with an electron beam are eliminated, so that the shape contour of a two-dimensional pattern before irradiating an electron beam can be restored with a high degree of accuracy, and the dimension of a pattern can be measured with a high degree of accuracy, using the restored image.

Claims

1. A scanning electron microscope comprising:

an electron source;

a convergent lens of converging an electron beam emitted from the electron source;

a deflection coil of scanning the electron beam on a sample;

a detector of detecting a secondary electron generated from the sample by irradiating the sample with the electron beam; and

calculating means for calculating a contour of a pattern of a surface of the sample based on an output of the detector;

wherein the calculating means corrects a contour of the pattern changed by irradiating the sample with the electron beam in accordance with a shape of the pattern.

2. The scanning electron microscope according to claim 1, further comprising:

displaying means for displaying the contour of the pattern after having been corrected.

3. The scanning electron microscope according to claim 1, wherein the shape of the pattern is a cross sectional shape of the pattern created at the sample.

4. The scanning electron microscope according to claim 1, wherein the shape of the pattern is a taper angle of a section of the pattern created at the sample.

5. The scanning electron microscope according to claim 1, wherein the pattern is a resist pattern created at the sample.

6. The scanning electron microscope according to claim 1, wherein the shape of the pattern is an angle of a pattern edge relative to a scanning direction of the electron beam, further comprising:

a corresponding diagram storing portion of storing a corresponding diagram of the angle of the pattern edge relative to the scanning direction of the electron beam and a size change amount of the pattern.

7. The scanning electron microscope according to claim 1, wherein the contour of the pattern before irradiating the sample with the electron beam is calculated by calculating respectively individual shape change amounts at specific portions of a two-dimensional pattern.

8. The scanning electron microscope according to claim 7, wherein the specific portions of the two-dimensional pattern are a curvature portion of the pattern, a front end portion of the pattern, and a portion having a different interval of the patterns contiguous to each other.

9. The scanning electron microscope according to claim 7, further comprising:

a restoring calculation portion of calculating the shape change amount by irradiating the sample with the electron beam by using a taper angle of a section of the pattern, a size change amount of the pattern, and a corresponding diagram storing portion of storing a corresponding diagram of an angle of a pattern edge relative to a scanning direction of the electron beam and the size change amount of the pattern when a restoring parameter amount of the specific portion of the two-dimensional pattern is made to be the size change amount,

wherein the contour of the pattern before irradiating the sample with the electron beam is calculated based on the shape change amount calculated by the restoring calculation portion.

10. The scanning electron microscope according to claim 7, further comprising:

a stress calculating portion of calculating a stress by which the specific portions of the pattern effect influences to each other,

wherein a position before irradiating the sample with the electron beam is calculated by using the stress calculating portion.

11. A scanning electron microscope comprising:

an electron source;

a convergent lens of converging an electron beam emitted from the electron source;

a deflection coil of scanning the electron beam on a sample;

a detector of detecting a secondary electron generated from the sample by irradiating the sample with the electron beam; and

calculating means for calculating a contour of a pattern of a surface of the sample based on an output of the detector, further comprising;

a shape storing portion of storing a shape parameter of the pattern of the sample observed previously;

a corresponding diagram storing portion of storing a correspondence of the shape parameter and a size change amount by changing a dimension by irradiating the sample with the electron beam; and

a restoring calculation portion of calculating a shape change amount by irradiating the sample with the electron beam from the shape storing portion and the corresponding diagram storing portion,

wherein the calculating means corrects the contour of the pattern before irradiating the sample with the electron beam based on the shape change amount calculated by the restoring calculation portion.

12. The scanning electron microscope according to claim 11, further comprising:

displaying means for displaying a contour of the pattern after having been corrected.

13. The scanning electron microscope according to claim 11, wherein the shape of the pattern is a cross sectional shape of the pattern created at the sample.

14. The scanning electron microscope according to claim 11, wherein the shape of the pattern is a taper angle of a section of the pattern created at the sample.

15. The scanning electron microscope according to claim 11, wherein the pattern is a resist pattern created at the sample.

16. The scanning electron microscope according to claim 11, wherein the shape of the pattern is an angle of a pattern edge relative to a scanning direction of the electron beam, further comprising:

a corresponding table storing portion of storing a corresponding diagram of the angle of the pattern edge relative to the scanning direction of the electron beam and the size change amount of the pattern.

17. The scanning electron microscope according to claim 11, wherein a contour of the pattern before irradiating the sample with the electron beam is calculated by calculating the respectively individual shape change amounts at specific portions of a two-dimensional pattern.

18. The scanning electron microscope according to claim 17, wherein the specific portions of the two-dimensional pattern are a curvature portion, a front end portion of the pattern, and a portion having a different interval of the patterns contiguous to each other.

19. The scanning electron microscope according to claim 17, further comprising:

a restoring calculation portion of calculating the shape change amount by irradiating the sample with the electron beam by using a taper angle of a section of the pattern, the size change amount of the pattern, and a corresponding diagram storing portion of storing a corresponding diagram of an angle of a pattern edge relative to the scanning direction of the electron beam and the size change amount of the pattern when a restoring parameter amount of the specific portion of the two-dimensional pattern is made to be the size change amount,

wherein the contour of the pattern before irradiating the sample with the electron beam is calculated based on the shape change amount calculated by the restoring calculation portion.

20. The scanning electron microscope according to claim 17, further comprising:

a stress calculating portion of calculating a stress by which the specific portions of the pattern effect influences to each other,

wherein a position before irradiating the sample with the electron beam is calculated by using the stress calculating portion.