Focus blur measurement and control method

• US 20070041003A1
• Filed: 08/18/2005
• Published: 02/22/2007
• Est. Priority Date: 08/18/2005
• Status: Active Grant

• Current Assignee: GlobalFoundries, Inc.
• Original Assignee: International Business Machines Corporation
• Inventors: Ausschnitt, Christopher, Corliss, Daniel, Butt, Shahid, Brunner, Timothy
• Granted Patent: US 7,439,001 B2
• Time in Patent Office: Days
• US Class Current: 355/55
• CPC Class Codes: G03F 7/70533 Controlling abnormal operating mode, e.g. taking account of waiting time, decision to rework or rework flow
• CPC Class Codes: G03F 7/70625 Dimensions, e.g. line width, critical dimension [CD], profile, sidewall angle or edge roughness
• CPC Class Codes: G03F 7/70641 Focus

Abstract

A method for optimizing imaging and process parameter settings in a lithographic pattern imaging and processing system. The method includes correlating the dimensions of a first set of at least one control pattern printed in a lithographic resist layer, measured at three or more locations on or within the pattern which correspond to differing dose, defocus and blur sensitivity. The method then includes measuring the dimensions on subsequent sets of control patterns, printed in a lithographic resist layer, at three or more locations on or within each pattern, of which a minimum of three locations match those measured in the first set, and determining the effective dose, defocus and blur values associated with forming the subsequent sets of control patterns by comparing the dimensions at the matching locations with the correlated dependencies.

Claims

1. A method for optimizing imaging and process parameter settings in a lithographic pattern imaging and processing system, the method comprising:

correlating the dimensions of a first set of at least one control pattern printed in a lithographic resist layer, measured at three or more locations on or within the pattern which correspond to differing dose, defocus and blur sensitivity;

measuring the dimensions on subsequent sets of control patterns, printed in a lithographic resist layer, at three or more locations on or within each pattern, of which a minimum of three locations match those measured in the first set; and

determining the effective dose, defocus and blur values associated with forming the subsequent sets of control patterns by comparing the dimensions at the matching locations with the correlated dependencies.

2. The method of claim 1 wherein the locations of high defocus sensitivity on or within a pattern correspond to different heights on the profile in the resist layer resulting from the image of a low density pattern and the location of low defocus sensitivity corresponds to a single height on the profile in the resist layer resulting from the image of a high density pattern.

3. The method of claim 1 wherein the dimensions of the first set of at least one control pattern is measured at different blur condition of the pattern imaging system, the different blur conditions being varied by changing bandwidth of illumination in the lithographic pattern imaging and processing system.

4. The method of claim 1 wherein the dimensions of the first set of at least one control pattern is measured at different blur condition of the pattern imaging system, the different blur conditions being varied by changing tilt of an image plane in the lithographic pattern imaging and processing system.

5. The method of claim 1 wherein the dimensions at the three or more locations are measured simultaneously.

6. The method of claim 1 wherein the locations of high defocus and blur sensitivity comprise isolated features for which pitch to an adjacent feature is significantly greater than twice the width of the smallest feature dimension.

7. The method of claim 1 wherein the locations of low defocus and blur sensitivity comprise nested features for which pitch to an adjacent feature is not significantly greater than twice the width of the smallest feature dimension.

8. The method of claim 1 wherein the locations of high defocus sensitivity comprise isolated features for which pitch to an adjacent feature is significantly greater than twice the width of the smallest feature dimension, and the locations of low defocus sensitivity comprise nested features for which pitch to an adjacent feature is not significantly greater than twice the width of the smallest feature dimension.

9. A method for optimizing imaging and process parameter settings in a lithographic pattern imaging and processing system, the method comprising:

correlating the dimensions of a first set of at least one control pattern printed in a lithographic resist layer, measured at three or more locations on or within the pattern which correspond to differing dose, defocus and blur sensitivity, the locations of high defocus sensitivity on or within a pattern corresponding to different heights on the profile in the resist layer resulting from the image of a low density pattern and the location of low defocus sensitivity corresponding to a single height on the profile in the resist layer resulting from the image of a high density pattern, the dimensions of the first set of at least one control pattern being measured at different blur condition of the pattern imaging system varied by changing bandwidth of illumination or tilt of an image plane in the lithographic pattern imaging and processing system;

measuring the dimensions on subsequent sets of control patterns, printed in a lithographic resist layer, at three or more locations on or within each pattern, of which a minimum of three locations match those measured in the first set; and

determining the effective dose, defocus and blur values associated with forming the subsequent sets of control patterns by comparing the dimensions at the matching locations with the correlated dependencies.

10. The method of claim 9 wherein the locations of high defocus and blur sensitivity comprise isolated features for which pitch to an adjacent feature is significantly greater than twice the width of the smallest feature dimension.

11. The method of claim 9 wherein the locations of low defocus and blur sensitivity comprise nested features for which pitch to an adjacent feature is not significantly greater than twice the width of the smallest feature dimension.

12. The method of claim 9 wherein the locations of high defocus sensitivity comprise isolated features for which pitch to an adjacent feature is significantly greater than twice the width of the smallest feature dimension, and the locations of low defocus sensitivity comprise nested features for which pitch to an adjacent feature is not significantly greater than twice the width of the smallest feature dimension.

13. A method of determining blur error in lithographic imaging comprising:

providing nested and isolated features in a design to be lithographically patterned on a substrate;

lithographically patterning the nested and isolated features on a substrate at different focus settings for different blur conditions;

measuring dimensions of the nested feature at the different focus settings for the different blur conditions;

measuring dimensions of the isolated feature at the different focus setting for the different radiation blur conditions; and

determining contribution of blur error based on shifts in the dimension of the isolated feature at the different focus setting for the different blur conditions with respect to dimensions of the nested feature.

14. The method of claim 13 wherein the dimensions of the nested and isolated features are measured simultaneously.

15. The method of claim 13 further including determining exposure dose error based on any shifts in the dimension of the isolated feature at the different focus setting for the different blur conditions with respect to dimensions of the nested feature.

16. The method of claim 13 further including determining focus error based on any shifts in the dimension of the isolated feature at the different focus setting for the different blur conditions with respect to dimensions of the nested feature.

17. The method of claim 13 wherein the dimension of the isolated feature is sensitive to, and the dimension of the nested feature is relatively insensitive to, the different focus setting for the different blur conditions.

18. The method of claim 13 wherein the different blur conditions comprise different spectral widths of radiation used for the lithographic patterning or different tilts of the image plane.

19. The method of claim 13 wherein the different blur conditions comprise different spectral widths of radiation used for the lithographic patterning.

20. The method of claim 13 wherein the different blur conditions comprise different tilts of the image plane.