Continuous direct-write optical lithography

• US 7,167,296 B2
• Filed: 08/21/2003
• Issued: 01/23/2007
• Est. Priority Date: 08/24/2002
• Status: Expired due to Term

• Current Assignee: Chime Ball Technology Co., Ltd.
• Original Assignee: Maskless Lithography, Inc.
• Inventors: Meisburger, William Daniel
• Primary Examiner(s): Harrington; Alicia M.
• Assistant Examiner(s): THOMAS, BRANDI N
• Application Number:
  US10/646,525
• Publication Number:
  US 20040075882A1
• Time in Patent Office: 1,251 Days
• Field of Search: 359/290, 359/291, 359/292, 359/298, 359/224, 355/53, 355/67, 355/71
• US Class Current: 359/290
• CPC Class Codes: G03F 7/70216 Mask projection systems
• CPC Class Codes: G03F 7/70275 Multiple projection paths, e.g. array of projection systems, microlens projection systems or tandem projection systems
• CPC Class Codes: G03F 7/70283 Mask effects on the imaging process
• CPC Class Codes: G03F 7/70291 Addressable masks, e.g. spatial light modulators [SLMs], digital micro-mirror devices [DMDs] or liquid crystal display [LCD] patterning devices
• CPC Class Codes: G03F 7/70383 Direct write, i.e. pattern is written directly without the use of a mask by one or multiple beams maskless lithography using a programmable mask G03F7/70291
• 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 7/70508 Data handling in all parts of the microlithographic apparatus, e.g. handling pattern data for addressable masks or data transfer to or from different components within the exposure apparatus
• CPC Class Codes: G03F 7/70558 Dose control, i.e. achievement of a desired dose

Abstract

An optical lithography system comprises a light source, a spatial light modulator, imaging optics and means for continuously moving a photosensitive substrate relative to the spatial light modulator. The spatial light modulator comprises at least one array of individually switchable elements. The spatial light modulator is continuously illuminated and an image of the spatial light modulator is continuously projected on the substrate; consequently, the image is constantly moving across the surface of the substrate. While the image is moving across the surface, elements of the spatial light modulator are switched such that a pixel on the surface of the substrate receives, in serial, doses of energy from multiple elements of the spatial light modulator, thus forming a latent image on the substrate surface. The imaging optics is configured to project a blurred image of the spatial light modulator on the substrate, enabling sub-pixel resolution feature edge placement.

Claims

1. A lithographic tool for patterning a substrate, comprising:

a spatial light modulator, said spatial light modulator comprising an area array of individually switchable elements;

a light source configured to illuminate said spatial light modulator;

imaging optics configured to project a blurred image of said spatial light modulator on said substrate; and

an image movement mechanism for moving said image across the surface of said substrate.

2. A lithographic tool as in claim 1, wherein said spatial light modulator comprises a digital micro-mirror device.

3. A lithographic tool as in claim 1, wherein said light source is a continuous light source.

4. A lithographic tool as in claim 1, wherein said light source is an arc lamp.

5. A lithographic tool as in claim 1, wherein said light source is a laser.

6. A lithographic tool as in claim 5, wherein said laser is a continuous laser.

7. A lithographic tool as in claim 5, wherein said laser is a quasi-continuous laser.

8. A lithographic tool as in claim 1, wherein said imaging optics is a telecentric projection lens system.

9. A lithographic tool as in claim 1, wherein said imaging optics is configured to form a defocused image of said spatial light modulator.

10. A lithographic tool as in claim 1, wherein said imaging optics comprises a diffuser configured to blur said image of said spatial light modulator.

11. A lithographic tool as in claim 1, wherein said imaging optics has a numerical aperture adjusted such that said image of said spatial light modulator is blurred.

12. A lithographic tool as in claim 1, wherein said imaging optics comprises a microlens array configured to blur said image of said spatial light modulator.

13. A lithographic tool as in claim 1, wherein said imaging optics comprises a single projection lens system.

14. A lithographic tool as in claim 1, wherein said image movement mechanism comprises a stage on which said substrate is carried.

15. A lithographic tool as in claim 1, wherein said image movement mechanism comprises a stage on which said spatial light modulator is carried.

16. A lithographic tool as in claim 15, wherein said imaging optics is carried on said stage.

17. A lithographic tool as in claim 1, wherein said image movement mechanism comprises rotatable, spaced apart, axially parallel film drums, said substrate being wrapped around and tensioned between said drums.

18. A lithographic tool as in claim 1, further comprising a control computer configured to control switching said elements of said spatial light modulator while said image is moving across the surface of said substrate.

19. A lithographic tool as in claim 1, further comprising a substrate height measuring system.

28. A lithographic tool as in claim 1, wherein said spatial light modulator is a diffractive device.

29. A lithographic tool as in claim 1, wherein said spatial light modulator is a liquid crystal device.

20. A lithographic tool for patterning a substrate, comprising:

a plurality of spatial light modulators, each of said plurality of spatial light modulators comprising an area array of individually switchable elements;

a light source configured to illuminate said plurality of spatial light modulators;

a multiplicity of projection lens systems configured to project a blurred images of each one of said plurality of spatial light modulators on said substrate; and

an image movement mechanism for moving said image across the surface of said substrate;

wherein the number of said spatial light modulators is greater than the number of said projection lens systems.

21. A lithographic tool as in claim 20, wherein said number of projection lens systems is a submultiple of said number of spatial light modulators.

22. A lithographic tool for patterning a substrate, comprising:

a spatial light modulator, said spatial light modulator comprising an array of individually switchable elements;

a light source configured to illuminate said spatial light modulator;

imaging optics configured to project a blurred image of said spatial light modulator on said substrate;

a light switching mechanism positioned on a light path, said light path going from said light source to said spatial light modulator and ending at said substrate, said light switching mechanism being configured to control passage of light along said light path; and

an image movement mechanism for moving said image across the surface of said substrate.

23. A lithographic tool as in claim 22, wherein said light switching mechanism is a second spatial light modulator.

24. A lithographic tool as in claim 22, wherein said light switching mechanism is a shutter.

25. A lithographic tool as in claim 22, wherein said light switching mechanism is integrated with said light source.

26. A lithographic tool for patterning a substrate, comprising:

a first spatial light modulator, said first spatial light modulator comprising an area array of individually switchable elements;

a light source configured to illuminate said first spatial light modulator;

imaging optics configured to project a blurred image of said first spatial light modulator on said substrate;

a second spatial light modulator positioned on a light path, said light path going from said light source to said first spatial light modulator and ending at said substrate, said second spatial light modulator being configured to control passage of light along said light path; and

an image movement mechanism for moving said image across the surface of said substrate.

27. A lithographic tool for patterning a substrate, comprising:

a plurality of spatial light modulators, each of said spatial light modulators comprising an area array of individually switchable elements;

a light source configured to illuminate said plurality of spatial light modulators;

imaging optics configured to project blurred images of each one of said plurality of spatial light modulators on said substrate, at least two of said images of said spatial light modulators overlapping in register; and

an image movement mechanism for moving said images across the surface of said substrate.

30. A lithographic tool for patterning a substrate, comprising:

a plurality of spatial light modulators, each of said plurality of spatial light modulators comprising an area array of individually switchable elements;

a light source configured to illuminate said plurality of spatial light modulators;

imaging optics configured to project a blurred image of said plurality of spatial light modulators on said substrate; and

an image movement mechanism for moving said image across the surface of said substrate.

31. A lithographic tool as in claim 30, wherein said plurality of spatial light modulators are arranged in at least one row, said at least one row being perpendicular to the direction of movement of said image across the surface of said substrate.

32. A lithographic tool as in claim 31, wherein said spatial light modulators are equally spaced within said row.

33. A lithographic tool as in claim 30, wherein said individually switchable elements are configured in rows and the direction of movement of said image across the surface of said substrate is perpendicular to said rows of elements.

34. A lithographic tool as in claim 30, wherein said plurality of spatial light modulators are arranged in multiple rows, said rows being perpendicular to the direction of movement of said image across the surface of said substrate.

35. A lithographic tool as in claim 34, wherein said spatial light modulators are equally spaced within said rows.

36. A lithographic tool as in claim 35, wherein the positions of said spatial light modulators are staggered from one row to the next.

37. A lithographic tool as in claim 36, wherein said spatial light modulators are configured such that each spatial light modulator exposes a non-overlapping swath of said substrate.

38. A lithographic tool as in claim 30, wherein said plurality of spatial light modulators are configured in a two-dimensional array.

39. A lithographic tool as in claim 30, wherein said plurality of spatial light modulators are configured to make most efficient use of said imaging optics.

40. A lithographic tool as in claim 39, wherein said plurality of spatial light modulators are arranged within a roughly circular area.

41. A lithographic tool as in claim 30, wherein said light source comprises a lens array configured to maximize the light intensity on each spatial light modulator in said plurality of spatial light modulators.

42. A lithographic tool as in claim 30, wherein said imaging optics comprises one projection lens system for each of said spatial light modulators.

43. A lithographic tool as in claim 42, wherein said projection lens systems are telecentric projection lens systems.