Off-axis catadioptric projection optical system for lithography

• US 20060023191A1
• Filed: 07/30/2004
• Published: 02/02/2006
• Est. Priority Date: 07/30/2004
• Status: Active Grant

• Current Assignee: ASML Holding NV
• Original Assignee: ASML Holding NV
• Inventors: Oskotsky, Mark, Smirnov, Stanislav
• Granted Patent: US 7,511,798 B2
• Time in Patent Office: Days
• US Class Current: 355/67
• CPC Class Codes: G02B 17/0812 off-axis or unobscured systems in which all of the mirrors share a common axis of rotational symmetry
• CPC Class Codes: G03B 27/54 Lamp housings; Illuminating means
• CPC Class Codes: G03F 7/70225 Optical aspects of catadioptric systems, i.e. comprising reflective and refractive elements

Abstract

The present invention is directed to off-axis catadioptric projection optical systems for use in lithography tools for processing modulated light used to form an image on a substrate, such as a semiconductor wafer or flat panel display. In one embodiment the optical system includes an off-axis mirror segment, a fold mirror, a relay, an aperture stop and a refractive lens group. Modulated light is transmitted through the system to form an image on a substrate. In a second embodiment the projection system includes an off-axis mirror segment, an aperture stop and a refractive lens group. In a third embodiment the projection system includes an off-axis mirror segment, a negative refractive lens group, a concave mirror, a relay, an aperture stop, and a refractive lens group. A method to produce a device using a lithographic apparatus including a projection system with an off-axis mirror segment as the first element in a projection optics system is also provided.

Claims

1. A projection system for use in a lithography tool for processing modulated light used to form an image on a substrate, comprising:

an off-axis mirror segment that receives modulated light;

an aperture stop that receives the modulated light from said off axis mirror segment and; and

a refractive lens group that focuses the modulated light onto the substrate.

2. The optical system of claim 1, further comprising a pattern generating device that provides the modulated light for use in forming the image on the substrate.

3. The optical system of claim 2, wherein said pattern generating device is a spatial light modulator.

4. The optical system of claim 1, wherein said off-axis mirror segment is concave.

5. The optical system of claim 1, wherein said off-axis mirror segment provides field curvature correction.

6. The optical system of claim 1, wherein said substrate is a semiconductor wafer or flat panel display.

7. An optical system for use in a lithography tool for processing modulated light used to form an image on a substrate, comprising;

an off-axis mirror segment that receives modulated light;

a fold mirror that receives the modulated light from said off-axis mirror segment;

a relay that receives the modulated light from said fold mirror and focusing the modulated light;

an aperture stop that receives the modulated light from said relay; and

a refractive lens group that focuses the modulated light onto the substrate.

8. The optical system of claim 7, further comprising a pattern generating device that provides the modulated light for use in forming an image on the substrate.

9. The optical system of claim 8, wherein said pattern generating device is a spatial light modulator.

10. The optical system of claim 8, wherein said off-axis mirror segment is concave.

11. The optical system of claim 8, wherein said off-axis mirror segment provides field curvature correction.

12. The optical system of claim 8, wherein said substrate is a semiconductor wafer or flat panel display.

13. An optical system for use in a lithography tool for processing modulated light used to form an image on a substrate, comprising;

an off-axis mirror segment that receives modulated light;

a concave mirror that receives modulated light from said off-axis mirror segment;

a negative refractive lens group positioned between said off-axis mirror segment and said concave mirror;

a relay that receives light from said concave mirror that has passed through said refractive lens group and that focuses the modulated light;

an aperture stop that receives the modulated light from said relay; and

a refractive lens group that focuses the modulated light onto the substrate.

14. The optical system of claim 13, further comprising a pattern generating device that provides the modulated light for use in forming an image on the substrate.

15. The optical system of claim 14, wherein said pattern generating device is a spatial light modulator.

16. The optical system of claim 13, wherein said off-axis mirror segment is concave.

17. The optical system of claim 13, wherein said off-axis mirror segment provides field curvature correction.

18. The optical system of claim 13, wherein said negative refractive lens group provides chromatic aberration reduction.

19. The optical system of claim 13, wherein said substrate is a semiconductor wafer or a flat panel display.

20. A lithographic apparatus, comprising:

an illumination system that supplies a projection beam of radiation;

a pattern generator that patterns the projection beam; and

a projection system that projects the patterned beam along a predetermined beam path onto a substrate, wherein said projection system comprises an off-axis mirror segment that receives the patterned beam from said pattern generator.

21. A method to produce a device using a lithographic apparatus comprising a projection system with an off axis mirror segment, comprising the steps of:

(a) emitting a projection beam;

(b) generating a patterned projection beam based on said radiation beam;

(c) reflecting said patterned projection beam with the off-axis mirror segment;

(d) focusing the reflected patterned projection beam; and

(e) imaging the reflected patterned projection beam onto a substrate to create the device.

22. The method of claim 21, wherein step (e) comprises imaging the reflected patterned projection beam onto a substrate to create an integrated circuit.

23. The method of claim 21, wherein step (e) comprises imaging the reflected patterned projection beam onto a substrate to create a flat panel display.