SYNTHESIZING LOW MASK ERROR ENHANCEMENT FACTOR LITHOGRAPHY SOLUTIONS

• US 20150234970A1
• Filed: 02/20/2014
• Published: 08/20/2015
• Est. Priority Date: 02/20/2014
• Status: Active Grant

• Current Assignee: GlobalFoundries, Inc.
• Original Assignee: International Business Machines Corporation
• Inventors: Rosenbluth, Alan E., Tian, Kehan, Inoue, Tadanobu, Melville, David O., Sakamoto, Masaharu
• Granted Patent: US 9,395,622 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: G03F 1/36 Masks having proximity correction features; Preparation thereof, e.g. optical proximity correction [OPC] design processes
• 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 7/00 Photomechanical, e.g. photolithographic, production of textured or patterned surfaces, e.g. printing surfaces; Materials therefor, e.g. comprising photoresists; Apparatus specially adapted therefor using photoresist structures for special production processes, see the relevant places, e.g. B44C, H01L, e.g. H01L21/00, H05K
• CPC Class Codes: G03F 7/70125 Use of illumination settings tailored to particular mask patterns details of setting means G03F7/70091
• CPC Class Codes: G03F 7/70425 Imaging strategies, e.g. for increasing throughput or resolution, printing product fields larger than the image field or compensating lithography- or non-lithography errors, e.g. proximity correction, mix-and-match, stitching or double patterning
• CPC Class Codes: G03F 7/70433 Layout for increasing efficiency or for compensating imaging errors, e.g. layout of exposure fields for reducing focus errors; Use of mask features for increasing efficiency or for compensating imaging errors
• CPC Class Codes: G06F 2119/18 Manufacturability analysis or optimisation for manufacturability
• CPC Class Codes: G06F 30/00 Computer-aided design [CAD]

Abstract

In one embodiment, a source mask optimization (SMO) method is provided that includes controlling bright region efficiency during at least one optical domain step. The bright region efficiency being the proportion of the total transmitted light that is transferred to bright areas of a target pattern. The optical domain intermediate solution provided by the at least one optical domain step may then be binarized to obtain an initial spatial domain solution with a controlled MEEF (Mask Error Enhancement Factor). The MEEF is controlled during at least one spatial domain step that optimizes the initial spatial domain solution.

Claims

1. A source mask optimization (SMO) method comprising:

controlling bright region efficiency during at least one optical domain step, the bright region efficiency being a proportion of a total transmitted light that is transferred to bright areas of a target pattern;

binarizing an optical domain intermediate solution provided by the at least one optical domain step to obtain an initial spatial domain solution with a controlled MEEF (Mask Error Enhancement Factor); and

controlling MEEF during at least one spatial domain step that optimizes the initial spatial domain solution.

2. The method of claim 1, wherein controlling bright region efficiency comprises setting bright region efficiency constraint using a joint eigenvector based mask optimization step, the joint eigenvectors being eigenvectors of matrix that relate intensity of light source and intensity on wafer and enable the derivation of a high contrast mask solution.

3. The method of claim 2, further comprising maintaining the bright region efficiency constraint through an entirety of a frequency domain optimization flow, wherein the frequency domain optimization flow includes a source initiation step, a mask optimization step, a source optimization step and a joint optimization step.

4. The method of claim 1, wherein the bright region efficiency comprises efficiency expressed by the equation:

Efficiency=(Power of Bright Area/Area of Bright)/(Power of Total Diffracted In Band Limit/Area of Total)

5. The method of claim 1, wherein controlling MEEF comprises introducing MEEF constraint/objective in wavefront engineering.

6. The method of claim 1, wherein binarizing the optical domain intermediate solution includes forming a bitmap mask.

7. The method of claim 5, wherein introducing MEEF constraint/objective comprises linearizing MEEF constraint by introducing variables into the wavefront engineering indicating the presence or absence of a transmission discontinuity.

8. The method of claim 5, wherein introducing MEEF constraint/objective comprises directly controlling MEEF during wavefront engineering to minimize a worst case MEEF.

9. A non-transitory computer readable storage medium comprising a computer readable program for performing a source mask optimization (SMO) method, wherein the non-transitory computer readable program when executed on a computer causes the computer to perform the steps of:

controlling bright region efficiency during at least one optical domain step, the bright region efficiency being a proportion of a total transmitted light that is transferred to bright areas of a target pattern;

binarizing an optical domain intermediate solution provided by the at least one optical domain step to obtain an initial spatial domain solution with a controlled MEEF (Mask Error Enhancement Factor); and

controlling MEEF during at least one spatial domain step that optimizes the initial spatial domain solution.

10. The program product according to claim 9, wherein controlling bright region efficiency comprises setting bright region efficiency constraint using a joint eigenvector based mask optimization step, the joint eigenvectors being eigenvectors of matrix that relate intensity of light source and intensity on wafer and enable the derivation of a high contrast mask solution.

11. The program product according to claim 10, further comprising integrating the bright region efficiency constraint through an entirety of a frequency domain.

12. The program product according to claim 11, wherein the frequency domain includes a source initiation step, a mask optimization step, a source optimization step and a joint optimization step.

13. The program product according to claim 12, wherein the bright region efficiency comprises efficiency expressed by the equation:

Efficiency=(Power of Bright Area/Area of Bright)/(Power of Total Diffracted In Band Limit/Area of Total)

14. The program product according to claim 9, wherein controlling MEEF comprises introducing MEEF constraint/objective in wavefront engineering.

15. The program product according to claim 9, wherein binarizing the optical domain intermediate solution includes forming a bitmap mask.

16. The program product according to claim 14, wherein introducing MEEF constraint/objective comprises linearizing MEEF constraint by introducing variables the wavefront engineering indicating the presence or absence of a transmission discontinuity.

17. The program product of claim 16, wherein introducing MEEF constraint/objective comprises directly controlling MEEF during wavefront engineering.

18. A method of patterning a semiconductor device comprising:

providing a mask that has been produced using a source mask optimization process that includes controlling MEEF during at least one step of the source mask optimization; and

patterning a photoresist layer using the mask.

19. The method of claim 18, wherein controlling MEEF during the source mask optimization includes controlling the MEEF during a spatial domain optimization.

20. The method of claim 18, wherein controlling MEEF during the source optimization includes controlling the MEEF during at least one frequency domain optimization.