Holographic patterning method and tool for production environments

• US 6,285,817 B1
• Filed: 04/17/2000
• Issued: 09/04/2001
• Est. Priority Date: 06/10/1996
• Status: Expired due to Fees

• Current Assignee: DMG Technologies, Inc.
• Original Assignee: Optical Switch Corporation
• Inventors: Hobbs, Douglas S.
• Primary Examiner(s): Palmer, Phan T.H.
• Application Number:
  US09/551,136
• Time in Patent Office: 505 Days
• Field of Search: 385/1, 385/4, 385/12, 385/14, 385/15, 385/24, 385/28, 385/31, 385/32, 385/33, 385/115, 385/116, 385/147, 359/619, 359/626, 219/121.6, 219/121.61, 219/121.75, 219/121.76, 250/227.23
• US Class Current: 385/147
• CPC Class Codes: G02B 6/2848 having refractive means, e.g. imaging elements between light guides as splitting, branching and/or combining devices, e.g. lenses, holograms
• CPC Class Codes: G02B 6/4204 the coupling comprising intermediate optical elements, e.g. lenses, holograms encapsulated active devices H01S5/02208, H01L33/52
• CPC Class Codes: G03F 7/001 Phase modulating patterns, e.g. refractive index patterns
• CPC Class Codes: G03F 7/2006 using coherent light; using polarised light
• CPC Class Codes: G03F 7/70408 Interferometric lithography; Holographic lithography; Self-imaging lithography, e.g. utilizing the Talbot effect
• CPC Class Codes: G03H 1/00 Holographic processes or apparatus using light, infrared or ultraviolet waves for obtaining holograms or for obtaining an image from them; Details peculiar thereto
• CPC Class Codes: G03H 2001/0094 for patterning or machining using the holobject as input light distribution microlithography G03F7/70283
• CPC Class Codes: H01J 2209/0223 Field emission cathodes

Abstract

A high resolution, high-throughout, large field size, production environment, lithographic tool system and method includes an interferometric pattern generator utilizing three or four mutually coherent optical beams organized in a flexible beam expansion, filtering, aperturing, and delivery system, large area pattern uniformity is attained via optimized illumination beam positioning and shaping. A passive stabilization system achieves fully modulated interferometric patterns in high mechanical and acoustical vibration manufacturing environments.

Claims

1. A holographic lithography system for generating an interference pattern suitable for selectively exposing a photosensitive material, comprising:

a platform for mounting a workpiece having a photosensitive surface; and

a beam delivery system configured to direct a plurality of illuminating beams toward said platform in an overlapping manner to form an optical interference pattern in the vicinity of the workpiece, said beam delivery system including;

a plurality of optical fibers having transmissive ends from which the illuminating beams respectively emanate divergently; and

a support structure on which the transmissive ends of the optical fibers are mounted, the transmissive ends being positioned and angled on said support structure such that the illuminating beams overlap to form the optical interference pattern that selectively exposes the photosensitive surface of the workpiece.

2. The system of claim 1, wherein the transmissive ends of the optical fibers are adjustably mounted on said support structure, such that positions and angles of the illuminating beams relative to said platform are adjustable by moving the transmissive ends of the optical fibers to different points on the support structure to thereby form the optical interference pattern that selectively exposes the photosensitive surface of the workpiece.

3. The system of claim 1, wherein said beam delivery system delivers illuminating beams having a wavelength in the blue range of the visible spectrum.

4. The system of claim 1, wherein said beam delivery system further includes:

a coherent light source generating a coherent light source beam;

a beam splitter circuit configured to divide the coherent light source beam into a plurality of coherent beams and launch the coherent beams into input ends of the optical fibers, the coherent beams emanating from the transmissive ends of the optical fibers as the illuminating beams.

5. The system of claim 4, wherein said coherent light source is an argon-ion gas laser and the coherent light source beam is a laser beam having a wavelength in the blue range of the visible spectrum.

6. The system of claim 1, wherein said beam delivery system generates two illuminating beams that overlap to form the optical interference pattern.

7. The system of claim 1, wherein said beam delivery system generates three illuminating beams that overlap to form the optical interference pattern.

8. The system of claim 1, wherein said beam delivery system generates four illuminating beams that overlap to form the optical interference pattern.

9. The system of claim 1, wherein a point of intersection of centers of the illuminating beams is in a reference plane lying substantially along the photosensitive surface of the workpiece.

10. The system of claim 1, wherein a point of intersection of centers of the illuminating beams is in a reference plane that is offset from the photosensitive surface of the workpiece by an offset distance.

11. The system of claim 10, wherein the offset distance is in the range between approximately five to ten centimeters.

12. The system of claim 1, wherein said platform is configured to receive a workpiece comprising a wafer having at least a substrate and a photoresist coating.

13. The system of claim 1, wherein said beam delivery system further includes optical elements respectively coupled to the transmissive ends of said optical fibers, said optical elements controlling divergence of the illuminating beams.

14. The system of claim 13, wherein said optical elements are refractive lenses.

15. The system of claim 13, wherein said optical elements are diffusing elements.

16. A method of performing holographic lithography for generating an interference pattern suitable for selectively exposing a photosensitive material, the method comprising the steps of:

(a) mounting a workpiece having a photosensitive surface on a platform;

(b) transmitting a plurality of divergent illuminating beams from transmissive ends of a plurality of optical fibers, the transmissive ends of the optical fibers being mounted on a support structure such that the illuminating beams are directed toward said platform in an overlapping manner to form an optical interference pattern in the vicinity of the workpiece; and

(c) exposing the photosensitive material with the optical interference pattern formed by the illuminating beams.

17. The method of claim 16, wherein step (b) includes adjustably mounting the transmissive ends of the optical fibers on the support structure, such that positions and angles of the illuminating beams relative to the photosensitive material are adjustable by moving the transmissive ends of the optical fibers to different points on the support structure.

18. The method of claim 16, wherein step (b) includes transmitting the illuminating beams through optical elements respectively coupled to the transmissive ends of the optical fibers to control divergence of the illuminating beams.

19. The method of claim 18, wherein the optical elements are refractive lenses.

20. The method of claim 18, wherein the optical elements are diffusing elements.

21. The method of claim 16, wherein step (b) further includes:

(b1) generating a coherent light source beam;

(b2) dividing the coherent light source beam into a plurality of coherent beams; and

(b3) launching the coherent beams into input ends of the optical fibers.

22. The method of claim 16, wherein step (b) includes generating illuminating beams having a wavelength in the blue range of the visible spectrum.

23. The method of claim 16, wherein step (b) includes generating two illuminating beams that overlap to form the optical interference pattern.

24. The method of claim 16, wherein step (b) includes generating three illuminating beams that overlap to form the optical interference pattern.

25. The method of claim 16, wherein step (b) includes generating four illuminating beams that overlap to form the optical interference pattern.

26. The method of claim 16, wherein a point of intersection of centers of the illuminating beams is in a reference plane lying substantially along a surface of the photosensitive material.

27. The method of claim 16, wherein a point of intersection of centers of the illuminating beams is in a reference plane that is offset from a surface of the photosensitive material by an offset distance.

28. The method of claim 27, wherein the offset distance is in the range between approximately five to ten centimeters.