Enhanced lithographic resolution through double exposure

• US 20070258073A1
• Filed: 07/11/2007
• Published: 11/08/2007
• Est. Priority Date: 01/28/2004
• Status: Abandoned Application

• Current Assignee: ASML Netherlands BV (ASML Holding NV)
• Original Assignee: ASML Netherlands BV (ASML Holding NV)
• Inventors: Flagello, Donis, Hansen, Steven, Finders, Jozef
• Application Number:
  US11/822,995
• Publication Number:
  US 20070258073A1
• Time in Patent Office: Days
• US Class Current: 355/53
• 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: 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

Abstract

A system and method for enhancing the image resolution in a lithographic system, is presented herein. The invention comprises decomposing a reticle pattern into at least two constituent sub-patterns that are capable of being optically resolved by the lithographic system, coating a substrate with a pre-specified photoresist layer, and exposing a first of the at least two constituent sub-patterns by directing a projection beam through the first sub-pattern such that the lithographic system produces a first sub-pattern image onto the pre-specified photoresist layer of the substrate. The invention further comprises processing the exposed substrate, exposing a second of the at least two constituent sub-patterns by directing the projection beam through the second sub-pattern such that the lithographic system produces a second sub-pattern image onto the pre-specified photoresist layer of the substrate, and then combining the first and second sub-pattern images to produce a desired pattern on the substrate.

Claims

1. A method of enhancing the image resolution in a lithographic system, comprising:

decomposing a pattern into at least two constituent sub-patterns;

coating a substrate with a pre-specified photoresist layer, said pre-specified photoresist layer having reduced memory reaction characteristics;

exposing a first of said at least two constituent sub-patterns by directing a projection beam onto said first sub-pattern such that said lithographic system produces a first sub-pattern image onto said pre-specified photoresist layer of said substrate;

processing said exposed substrate;

exposing a second of said at least two constituent sub-patterns by directing said projection beam onto said second sub-pattern such that said lithographic system produces a second sub-pattern image onto said pre-specified photoresist layer of said substrate,

wherein said exposing results in a combination of said first and second sub-pattern images to produce a desired pattern on said substrate.

2. The method of claim 1, wherein said lithographic system is capable of optically resolving pattern features that correspond to a half-pitch lower limit k₁ greater than 0.25 and said desired pattern includes features that correspond to a half-pitch lower limit k₁, less than or equal to 0.25.

3. The method of claim 1, wherein said processing includes,

baking said substrate having said first sub-pattern image on said photoresist layer, and

shifting said substrate, in said lithographic system, by a certain distance, in order to interleave said second sub-pattern image with said first sub-pattern image.

4. The method of claim 3, further including applying a developer solution to said substrate.

5. The method of claim 3, wherein said processing is optimized by employing specific bake times and temperatures such that said desired pattern includes features that correspond to a half-pitch lower limit k₁ less than or equal to 0.25.

6. The method of claim 1, wherein said pre-specified photoresist layer further comprises a polymer resin compound, a photo-acid generator component, and a base component.

7. The method of claim 3, wherein said processing further includes,

applying a developer solution to said substrate, and

shifting said substrate, in said lithographic system, by a certain distance, in order to combine said second sub-pattern image with said first sub-pattern image.

8. The method of claim 7, further including baking said substrate having said second sub-pattern image and a developed first sub-pattern image on said photoresist layer.

9. The method of claim 8, wherein said processing is optimized by employing specific bake times and temperatures such that said desired pattern includes features that correspond to a half-pitch lower limit k₁ less than or equal to 0.25.

10. The method of claim 9, wherein said pre-specified photoresist layer further comprises a polymer resin compound, a photo-acid generator component, and a base component.

11. The method of claim 3, further comprising shifting said substrate before exposing the second of said at least two constituent sub-patterns, in said lithographic system, by a certain distance, in order to interleave said second sub-pattern image with said first sub-pattern image.

12. An enhanced image resolution lithographic system, comprising:

a coating station configured to apply a photoresist layer onto a substrate, said photoresist layer configured to exhibit reduced memory reaction characteristics;

an exposure apparatus to expose a pattern onto said substrate; and

a processing station configured to process a substrate exposed by said exposure apparatus,

wherein said pattern is decomposed into at least two constituent sub-patterns that can be optically resolved by said exposure apparatus,

wherein a first of said at least two constituent sub-patterns is exposed onto said substrate by said exposure apparatus to produce a first sub-pattern image onto said photoresist layer of said substrate and said exposed substrate is processed by said processing station, and

wherein a second of said at least two constituent sub-patterns is exposed onto said substrate by said exposure apparatus to produce a second sub-pattern image onto said photoresist layer of said substrate and said first and second sub-pattern images are combined to produce a desired pattern.

13. The system of claim 12, wherein said exposure apparatus is capable of optically resolving pattern features that correspond to a half-pitch lower limit k₁ greater than 0.25 and said desired pattern includes features that correspond to a half-pitch lower limit k₁ less than or equal to 0.25.

14. The system of claim 12, wherein said processing station includes a baking station configured to bake said substrate having said first sub-pattern image on said photoresist layer.

15. The system of claim 14, configured to shift said substrate by a certain distance, in order to combine said second sub-pattern image with said first sub-pattern image.

16. The system of claim 14, configured to apply a developer solution to said substrate.

17. The system of claim 14, configured to optimize attributes of a baking of said substrate by employing specific bake times and temperatures such that said desired pattern includes features that correspond to a half-pitch lower limit k₁ less than or equal to 0.25.

18. The system of claim 12, wherein said photoresist layer further comprises a polymer resin compound, a photo-acid generator component, and a base component.

19. The system of claim 12, wherein said processing station further includes:

a baking station configured to bake said substrate having said first sub-pattern image on said photoresist layer, and

a developer station to apply developer solution to said substrate.

20. The system of claim 19, configured to shift said substrate by a certain distance, in order to combine said second sub-pattern image with said first sub-pattern image.

21. The system of claim 20, further configured to bake said substrate having said second sub-pattern image and a developed first sub-pattern image on said photoresist layer.

22. The system of claim 21, configured to optimize attributes of a baking of said substrate by employing specific bake times and temperatures such that said desired pattern includes features that correspond to a half-pitch lower limit k₁ less than or equal to 0.25.

23. The system of claim 22, wherein said photoresist layer further comprises a polymer resin compound, a photo-acid generator component, and a base component.