Off-axis catadioptric projection optical system for lithography

• US 7,834,979 B2
• Filed: 02/20/2009
• Issued: 11/16/2010
• Est. Priority Date: 07/30/2004
• Status: Expired due to Fees

• Current Assignee: ASML Holding NV
• Original Assignee: ASML Netherlands BV (ASML Holding NV)
• Inventors: Oskotsky, Mark, Smirnov, Stanislav
• Primary Examiner(s): Fuller; Rodney E
• Application Number:
  US12/389,593
• Publication Number:
  US 20090153954A1
• Time in Patent Office: 634 Days
• Field of Search: 355/53, 355/66
• US Class Current: 355/66
• 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

An off-axis catadioptric projection optical systems for use in lithography tools for processing modulated light used to form an image on a substrate is provided. 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. The projection system includes an off-axis mirror segment, an aperture stop and a refractive lens group. Alternatively, 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.

Claims

1. A system comprising:

a pattern generator having a surface that is configured to generate modulated light and associated with a first axis along and orthogonal to a center of the surface;

an off-axis mirror segment configured to receive the modulated light, a second axis, associated with the off-axis mirror segment, being spaced a distance from a third axis located along and orthogonal to a center of a surface of a substrate configured to receive an image from a projection system having multiple mirror segments, the off-axis mirror segment being the first minor segment within the projection system;

an aperture stop configured to receive the modulated light from the off-axis mirror segment; and

a refractive lens group configured to focus the modulated light onto the substrate,

wherein the first axis is different from the third.

2. The system of claim 1, wherein the pattern generating device is a spatial light modulator.

3. The system of claim 1, wherein the off-axis mirror segment is concave.

4. The system of claim 1, wherein the off-axis mirror segment provides field curvature correction.

5. The system of claim 1, wherein the substrate is a semiconductor wafer or flat panel display.

6. An optical system, comprising:

a pattern generator having a surface that is configured to generate modulated light and associated with a first axis along and orthogonal to a center of the surface;

an off-axis mirror segment configured to receive the modulated light, a second axis, associated with the off-axis mirror segment, being spaced a distance from a third axis located along and orthogonal to a center of a surface of a substrate, the off-axis mirror segment is a first mirror segment within the optical system;

a fold minor configured to receive the modulated light from the off-axis mirror segment;

a relay configured to receive the modulated light from the fold mirror and to focus the modulated light;

an aperture stop configured to receive the modulated light from the relay; and

a refractive lens group configured to focus the modulated light onto the substrate,

wherein the first axis is different from the third.

7. The optical system of claim 6, wherein the pattern generating device is a spatial light modulator.

8. The optical system of claim 6, wherein the off-axis minor segment is concave.

9. The optical system of claim 6, wherein the off-axis mirror segment provides field curvature correction.

10. An optical system, comprising:

a pattern generator having a surface that is configured to generate modulated light and associated with a first axis along and orthogonal to a center of the surface;

an off-axis mirror segment configured to receive the modulated light, a second axis, associated with the off-axis mirror segment, being spaced a distance from a third axis located along and orthogonal to a center of a surface of the substrate, the off-axis minor segment being a first minor within the optical system;

a concave mirror configured to receives modulated light from the off-axis mirror segment;

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

a relay configured to receive light from the concave minor configured to have passed through the refractive lens group and configured to focuses the modulated light;

an aperture stop configured to receives the modulated light from the relay; and

a refractive lens group configured to focuses the modulated light onto the substrate,

wherein the first axis is different from the third.

11. The optical system of claim 10, wherein the pattern generating device is a spatial light modulator.

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

13. The optical system of claim 10, wherein the off-axis mirror segment provides field curvature correction.

14. The optical system of claim 10, wherein the negative refractive lens group provides chromatic aberration reduction.

15. The optical system of claim 10, wherein the substrate is a semiconductor wafer or a flat panel display.

16. A method comprising:

using a surface of a pattern generator to generate a patterned beam;

reflecting the patterned beam with the off-axis mirror segment;

focusing the reflected patterned beam; and

using a projection system to image the reflected patterned beam onto a surface of a substrate, wherein;

the surface of the pattern generator is associated with a first axis along and orthogonal to a center of the surface of the pattern generator,

a second axis associated with the off-axis mirror segment is spaced a distance from a third axis located along and orthogonal to a center of the surface of the substrate,

the first axis is different from the third, and

the off-axis mirror segment is a first mirror segment within the projection system.

17. The method of claim 16, wherein the imaging comprises imaging the reflected patterned beam onto a substrate to create an integrated circuit.

18. The method of claim 16, wherein the imaging comprises imaging the reflected patterned beam onto the substrate to create a flat panel display.