Method and system for design of enhanced edge slope patterns for charged particle beam lithography

• US 9,612,530 B2
• Filed: 03/11/2016
• Issued: 04/04/2017
• Est. Priority Date: 02/28/2011
• Status: Active Grant

• Current Assignee: D2S, Inc.
• Original Assignee: D2S, Inc.
• Inventors: Fujimura, Akira, Hagiwara, Kazuyuki, Meier, Stephen F., Bork, Ingo
• Primary Examiner(s): Ngo, Brian
• Application Number:
  US15/068,516
• Publication Number:
  US 20160195805A1
• Time in Patent Office: 389 Days
• Field of Search: 716 50, 716 51, 716 52, 716 53, 716 54, 716 55
• CPC Class Codes: G03F 1/68 Preparation processes not covered by groups G03F1/20 - G03F1/50
• CPC Class Codes: G03F 1/70 Adapting basic layout or design of masks to lithographic process requirements, e.g., second iteration correction of mask patterns for imaging
• CPC Class Codes: G03F 7/2061 Electron scattering (proximity) correction or prevention methods
• CPC Class Codes: G03F 7/2063 for the production of exposure masks or reticles
• CPC Class Codes: G06F 30/20 Design optimisation, verification or simulation optimisation, verification or simulation of circuit designs G06F30/30
• CPC Class Codes: H01J 2237/31771 using multiple exposure
• CPC Class Codes: H01J 37/3026 Patterning strategy
• CPC Class Codes: H01J 37/3177 Multi-beam, e.g. fly's eye, comb probe

Abstract

A method and system for fracturing or mask data preparation are presented in which a set of shots is determined for a multi-beam charged particle beam writer. The edge slope of a pattern formed by the set of shots is calculated. An edge of the pattern which has an edge slope below a target level is identified, and the dosage of a beamlet in a shot in the set of shots is increased to improve the edge slope. The improved edge slope remains less than the target level.

Claims

1. A method for fracturing or mask data preparation comprising:

inputting an original set of shots for a multi-beam charged particle beam writer, wherein each multi-beam shot in the original set of shots comprises at least one beamlet; and

dosages for the original set of shots have not been corrected for long-range effects;

calculating an edge slope of a pattern produced on a resist-coated surface by the original set of shots;

identifying an edge of the pattern which has an edge slope below a target level;

increasing the dosage of a beamlet in a shot in the original set of shots to improve the edge slope of the edge that has the edge slope below the target level, wherein the improved edge slope is closer to, without exceeding, the target level, wherein the resist comprises a resist threshold, and wherein the edge slope comprises a slope of the dosage, at the resist threshold, with respect to a linear dimension perpendicular to the edge of the pattern; and

outputting a revised set of shots to the multi-beam charged particle beam writer, wherein the revised set of shots revises the original set of shots with the increased dosage of a beamlet in a shot in the original set of shots.

2. The method of claim 1 wherein dosages in the original set of shots are not increased for edges of the pattern which have edge slopes equal to or above the target level.

3. The method of claim 1 wherein the target level is determined by one of i) fabricating a test chip based on a test design, and measuring critical dimensions (CD) of the test chip;

and ii) simulating an edge slope of a feature that is known to meet a manufacturing variation criterion.

4. The method of claim 3 wherein the test design is fabricated for a plurality of process conditions, and the target level of edge slope is determined from the process condition that meets the manufacturing variation criterion.

5. The method of claim 4, wherein the manufacturing variation criterion comprises one of the group consisting of:

critical dimension uniformity, line edge roughness and line width roughness.

6. The method of claim 1, wherein the edge of the pattern which has an edge slope below a target level is a line end.

7. The method of claim 6, wherein the edge of the pattern which has the edge slope below the target level is a corner of the line end.

8. A method for fracturing or mask data preparation or proximity effect correction comprising:

inputting an original set of shots for a multi-beam charged particle beam writer, wherein each multi-beam shot in the original set of shots comprises at least one beamlet;

calculating an edge slope of a pattern produced on a resist-coated surface by the original set of shots, including correction for long-range effects;

identifying an edge in the pattern which has an edge slope below a target level;

increasing the dosage of a beamlet in a shot in the original set of shots to improve the edge slope of the edge that has the edge slope below the target level, wherein the improved edge slope is closer to, without exceeding, the target level, wherein the resist comprises a resist threshold, and wherein the edge slope comprises a slope of the dosage, at the resist threshold, with respect to a linear dimension perpendicular to the edge of the pattern; and

outputting a revised set of shots to the multi-beam charged particle beam writer, wherein the revised set of shots revises the original set of shots with the increased dosage of a beamlet in a shot in the original set of shots.

9. The method of claim 8 wherein dosages in the original set of shots are not increased for edges of the pattern which have edge slopes equal to or above the target level.

10. The method of claim 8 wherein the long-range effects include backscattering and fogging.

11. A method for fracturing or mask data preparation or proximity effect correction comprising:

determining a plurality of shots for a multi-beam charged particle beam writer, wherein each shot in the plurality of shots comprises at least one beamlet, wherein the plurality of shots forms a pattern on a resist-coated surface, wherein the step of determining comprises calculating an edge slope of the pattern formed from the plurality of shots before correction for long-range effects;

identifying an edge of the pattern which has an edge slope below a target level;

increasing the dosage of a beamlet in a shot in the plurality of shots to improve the edge slope of the edge that has the edge slope below the target level, wherein the improved edge slope is closer to, without exceeding, the target level, wherein the resist comprises a resist threshold, and wherein the edge slope comprises a slope of the dosage, at the resist threshold, with respect to a linear dimension perpendicular to the edge of the pattern; and

outputting a revised plurality of shots to the multi-beam charged particle beam writer, wherein the revised plurality of shots revises the plurality of shots with the increased dosage of a beamlet in a shot in the plurality of shots.

12. The method of claim 11 wherein the improved edge slope remains less than the target level.

13. The method of claim 11 wherein dosage is not increased for edges of the pattern which have edge slopes equal to or above the target level.

14. A method for fracturing or mask data preparation or proximity effect correction comprising:

determining a plurality of shots for a multi-beam charged particle beam writer, wherein each shot in the plurality of shots comprises at least one beamlet, wherein the plurality of shots forms a pattern on a resist-coated surface;

performing proximity effect correction (PEC) to correct shot dosages for long-range effects for the plurality of shots;

calculating an edge slope of the pattern formed from the plurality of shots on a resist-coated surface;

identifying an edge of the pattern which has an edge slope below a target level;

increasing the dosage of a beamlet in a shot in the plurality of shots to improve the edge slope of the edge that has the edge slope below the target level, wherein the improved edge slope is closer to, without exceeding, the target level, wherein the resist comprises a resist threshold, and wherein the edge slope comprises a slope of the dosage, at the resist threshold, with respect to a linear dimension perpendicular to the edge of the pattern; and

outputting a revised set of shots to the multi-beam charged particle beam writer, wherein the revised set of shots revises the original set of shots with the increased dosage of a beamlet in a shot in the original set of shots.

15. The method of claim 14 wherein the increasing the dosage results in a modified plurality of shots, and wherein the method further comprises performing proximity effect correction (PEC) on the modified plurality of shots.

16. The method of claim 14 wherein the improved edge slope remains less than the target level.