Method, program product and apparatus for performing a model based coloring process for geometry decomposition for use in a multiple exposure process

• US 8,340,394 B2
• Filed: 07/24/2009
• Issued: 12/25/2012
• Est. Priority Date: 07/28/2008
• Status: Active Grant

• Current Assignee: ASML Netherlands BV (ASML Holding NV)
• Original Assignee: ASML Netherlands BV (ASML Holding NV)
• Inventors: Socha, Robert John
• Primary Examiner(s): Punnoose, Roy M
• Application Number:
  US12/509,389
• Publication Number:
  US 20100021055A1
• Time in Patent Office: 1,250 Days
• Field of Search: 382/145, 716/52, 716/53, 716/54
• US Class Current: 382/145
• 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 7/70283 Mask effects on the imaging process
• CPC Class Codes: G03F 7/70466 Multiple exposures, e.g. combination of fine and coarse exposures, double patterning or multiple exposures for printing a single feature stitching G03F7/70475
• CPC Class Codes: G03F 7/70475 Stitching, i.e. connecting image fields to produce a device field, the field occupied by a device such as a memory chip, processor chip, CCD, flat panel display

Abstract

A method of decomposing a target pattern having features to be imaged on a substrate so as to allow said features to be imaged in a multi-exposure process. The method includes

• • the steps of: (a) dividing a plurality of the features into a plurality of segments; (b) determining the image log slope (ILS) value for each of the plurality of segments; (c) determining the value of the gradient of the image log slope (ILS) value for each of the plurality of segments; and (d) assigning a phase or color to the segments based on the values of the gradient of the image log slope of each of the plurality of segments.

Claims

1. A method of decomposing a target pattern having features to be imaged on a substrate so as to allow said features to be imaged in a multi-exposure process, said method comprising the steps of:

(a) dividing a plurality of said features into a plurality of segments;

(b) determining the image log slope (ILS) value for each of said plurality of segments;

(c) determining the value of the gradient of the image log slope (ILS) value for each of said plurality of segments; and

(d) assigning a phase or color to said segments based on the values of the gradient of the image log slope of each of said plurality of segments.

2. A method according to claim 1, further comprising:

(e) placing one or more evaluation points on the plurality of segments,

wherein (b) determining the ILS value for the plurality of segments is performed at the one or more evaluation points.

3. A method according to claim 2, wherein (e) placing the evaluation points includes placing the evaluation points at edges of the plurality of segments.

4. A method according to claim 2, wherein (e) placing the evaluation points includes placing exactly one evaluation point on each of the plurality of segments.

5. A method according to claim 1, wherein (a) dividing the plurality of features is performed so that each of the segments is substantially the same size.

6. A method according to claim 1, wherein (a) dividing the plurality of features includes, for a given feature, projecting a ray from a vertex within the given feature to another point within the feature.

7. A method according to claim 6, wherein the ray has a length substantially equal to a minimum resolvable space for an exposure in the multi-exposure process.

8. A method according to claim 1, wherein (a) dividing the plurality of features includes pixelizing the features, wherein each pixel comprises a segment.

9. A method according to claim 8, wherein the size of each pixel corresponds to a resolution of a mask writer used for the multi-exposure process.

10. A method according to claim 1, further comprising (e) ordering one or both of the determined ILS values and gradient values from highest to lowest.

11. A method comprising:

identifying a target pattern for a multi-exposure process;

segmenting the target pattern into a plurality of segments;

calculating a model-based image value for each of the plurality of segments; and

assigning the segments to respective exposures in the multi-exposure process using the calculated model-based image value.

12. A method according to claim 11, further comprising identifying illumination settings for the multi-exposure process, wherein calculating the model-based image value is performed using the identified illumination settings.

13. A method according to claim 11, further comprising:

placing one or more evaluation points on the plurality of segments,

wherein calculating the model-based image value for the plurality of segments is performed at the one or more evaluation points.

14. A method according to claim 13, wherein placing the evaluation points includes placing the evaluation points at edges of the plurality of segments.

15. A method according to claim 13, wherein placing the evaluation points includes placing exactly one evaluation point on each of the plurality of segments.

16. A method according to claim 11, wherein segmenting the target pattern is performed so that each of the segments is substantially the same size.

17. A method according to claim 11, wherein segmenting the target pattern includes pixelizing the target pattern, wherein each pixel comprises a segment.

18. A method according to claim 17, wherein the size of each pixel corresponds to a resolution of a mask writer used for the multi-exposure process.

19. A method according to claim 11, wherein assigning the segments includes performing an iterative process including:

selecting one of the segments based on the calculated model-based image value;

assigning the segment to an exposure;

performing further calculations based on the assignment; and

re-assigning or keeping the assignment based on the further calculations.

20. A non-transitory computer readable storage medium comprising instructions, which when executed by a computer, cause the computer to perform a method of decomposing a target pattern having features to be imaged on a substrate so as to allow said features to be imaged in a multi-exposure process, said method comprising the steps of:

(a) dividing a plurality of said features into a plurality of segments;

(b) determining the image log slope (ILS) value for each of said plurality of segments;

(c) determining the value of the gradient of the image log slope (ILS) value for each of said plurality of segments; and

(d) assigning a phase or color to said segments based on the values of the gradient of the image log slope of each of said plurality of segments.