Methods, apparatus, and systems for minimizing defectivity in top-coat-free lithography and improving reticle CD uniformity

Patent metadata

Field	Value
Publication number	US-9798244-B2
Application number	US-201514943086-A
Country	US
Kind code	B2
Filing date	Nov 17, 2015
Priority date	Nov 17, 2015
Publication date	Oct 24, 2017
Grant date	Oct 24, 2017

Abstract

Methods, apparatus, and system for minimizing defectivity in top-coat-free immersion photolithography are provided. Embodiments include forming a photomask by defining a first pattern including a main functional pattern in the photomask; and defining a second pattern including a sub-resolution fill pattern in the photomask in areas between or and/or within structures of the first pattern, the fill pattern having a pitch or range of pitches smaller than a minimum resolved pitch of the lithographic exposure and/or at least a part of the sub-resolution structures of the sub-resolution fill pattern not substantially modifying an imaging of any structure of the main functional pattern in the lithographic exposure.

First claim

What is claimed is:

1. A method, comprising:
forming a photomask for a lithographic process comprising a lithographic exposure and a developing step, the forming comprising:
defining a first pattern in the photomask, the first pattern comprising a main functional pattern, the main functional pattern comprising structures; and
defining a second pattern in the photomask, the second pattern comprising a sub-resolution fill pattern in one or more areas between structures of the first pattern or within one or more structures of the first pattern, the sub-resolution fill pattern comprising sub-resolution structures that do not substantially modify a locally complete resist removal in the developing step, the sub-resolution fill pattern having a pitch or range of pitches smaller than a minimum resolved pitch of the lithographic exposure and/or at least a part of the sub-resolution structures of the sub-resolution fill pattern not substantially modifying an imaging of any structure of the main functional pattern in the lithographic exposure.

2. The method according to claim 1 , comprising:
defining the sub-resolution fill pattern to comprise a regular pattern in an area of the sub-resolution fill pattern, the regular pattern comprising alternating lines and spaces, or contact-like structures, or a combination thereof.

3. The method according to claim 2 , comprising:
defining the sub-resolution fill pattern to comprise a combination of dark and clear patterns.

4. The method according to claim 2 , comprising:
defining a pitch or a range of pitches of the regular pattern of the sub-resolution fill pattern, the pitch or range of pitches being smaller than a minimum resolved pitch of the lithographic exposure.

5. The method according to claim 4 , comprising:
defining the pitch or range of pitches to be smaller than 80 nanometers (nm).

6. The method according to claim 4 , comprising:
defining a direction of the regular pattern, the direction being a direction for which the minimum resolved pitch of the lithographic exposure has a maximum value.

7. The method according to claim 1 , comprising:
adjusting a size of the sub-resolution structures of the sub-resolution fill pattern to correspond to a predetermined background intensity in the lithographic exposure, and/or to a predetermined pattern density of the sub-resolution fill pattern.

8. The method according to claim 1 , comprising:
adjusting a size, a shape, and/or a position of one or more sub-resolution structures of the sub-resolution fill pattern in a border region of the sub-resolution fill pattern to optimize, in the lithographic exposure, a depth of focus and/or contrast of one or more structures of the main functional pattern in a vicinity of the one or more sub-resolution structures of the sub-resolution fill pattern.

9. The method according to claim 1 , the forming of the photomask further comprising:
writing the sub-resolution fill pattern with a reduced number and/or complexity of optical proximity corrections, a reduced number of writing passes, a reduced writing dose, a faster writing time, and/or a less advanced photomask writing tool compared to a number and/or complexity of optical proximity corrections, a number of writing passes, a writing dose, a writing time, and/or a photomask writing tool, respectively, used for a writing of the main functional pattern.

10. The method according to claim 1 , the forming of the photomask further comprising:
omitting an inspection or a part of an inspection for the sub-resolution fill pattern, or inspecting the sub-resolution fill pattern with a lower accuracy, a lower resolution, a faster inspection speed, a lower number of scans, and/or a less advanced inspection tool, compared to an accuracy, a resolution, an inspection speed, a number of scans, and/or an inspection tool, respectively, used for an inspection of the main functional pattern.

11. The method according to claim 1 , the forming of the photomask further comprising:
detecting a defect in the sub-resolution fill pattern, and omitting a repair process for the defect in the sub-resolution fill pattern, or repairing the defect in the sub-resolution fill pattern with a lower accuracy, a faster repair speed, a lower number of iterations, and/or a less advanced repair tool, compared to an accuracy, a repair speed, a number of iterations, and/or a repair tool, respectively, used for a repair process for the main functional pattern.

12. The method according to claim 1 , comprising:
providing a substrate coated with a photoresist without a top coat;
exposing the substrate in the lithographic exposure; and
developing the photoresist in the developing step.

13. A device, comprising:
a photomask for a lithographic process comprising a lithographic exposure and a developing step, the photomask comprising:
a first pattern, the first pattern comprising a functional pattern, the functional pattern comprising a main functional pattern, the main functional pattern comprising structures; and
a second pattern, the second pattern comprising a sub-resolution fill pattern defined in the photomask in one or more areas between structures of the first pattern or within one or a plurality of the structures of the first pattern, the sub-resolution fill pattern comprising sub-resolution structures, the presence of which does not substantially modify a locally complete resist removal in the developing step, the sub-resolution fill pattern having a pitch or range of pitches smaller than a minimum resolved pitch of the lithographic exposure and/or at least a part of the sub-resolution structures of the sub-resolution fill pattern not influencing an imaging of any structure of the main functional pattern in the lithographic exposure.

14. The device according to claim 13 , wherein the sub-resolution fill pattern comprises a regular pattern, the regular pattern comprising alternating lines and spaces or contact-like structures or a combination thereof.

15. The device according to claim 13 , wherein the sub-resolution fill pattern comprises a combination of dark and clear patterns.

16. The device according to claim 14 , wherein the regular pattern of the sub-resolution fill pattern comprises a pitch or range of pitches smaller than a minimum resolved pitch of the lithographic exposure.

17. The device according to claim 14 , wherein a direction of the regular pattern of the sub-resolution fill pattern is a direction for which the minimum resolved pitch of the lithographic exposure has a maximum value.

18. The device according to claim 13 , wherein a size of sub-resolution structures of the sub-resolution fill pattern corresponds to a predetermined background intensity in the lithographic exposure and/or a predetermined pattern density of the sub-resolution fill pattern.

19. The device according to claim 13 , wherein a size and/or shape and/or position of one or more sub-resolution structures of the sub-resolution fill pattern in a border region of the sub-resolution fill pattern is adjusted to optimize, in the lithographic exposure, a depth of focus or contrast of one or more structures of the main functional pattern.

20. A system comprising:
a processor or a plurality of processors, the processor or the plurality of processors configured to design a layout for a photomask for a chip layer and a lithography process for an exposure of a substrate with the photomask, the layout comprising a main functional pattern comprising structures, the processor or the plurality of processor

Assignees

• Globalfoundries Inc

Inventors

• Hotzel Arthur
• Jaschinsky Philipp
• Riviere Remi
• Grundke Wolfram

Classifications

• G03F1/50

  Mask blanks not covered by G03F1/20 - G03F1/34; Preparation thereof · CPC title

• G03F1/70 Primary

  Adapting basic layout or design of masks to lithographic process requirements, e.g., second iteration correction of mask patterns for imaging · CPC title

• G03F7/70325 Primary

  Resolution enhancement techniques not otherwise provided for, e.g. darkfield imaging, interfering beams, spatial frequency multiplication, nearfield lenses or solid immersion lenses · CPC title

• G03F1/36

  Masks having proximity correction features; Preparation thereof, e.g. optical proximity correction [OPC] design processes · CPC title