Projection optical system and method

• US 20060056064A1
• Filed: 09/01/2005
• Published: 03/16/2006
• Est. Priority Date: 09/03/2004
• Status: Active Grant

• Current Assignee: CARL Zeiss SMT GmbH (Carl-Zeiss-Stiftung)
• Original Assignee: Carl Zeiss AG (Carl-Zeiss-Stiftung)
• Inventors: Beder, Susanne, Shafer, Dave
• Granted Patent: US 7,301,707 B2
• Time in Patent Office: Days
• US Class Current: 359/727
• CPC Class Codes: G02B 13/143 for use with ultraviolet radiation
• CPC Class Codes: G02B 13/16 for use in conjunction with image converters or intensifiers , or for use with projectors, e.g. objectives for projection TV
• CPC Class Codes: G02B 13/22 Telecentric objectives or lens systems
• CPC Class Codes: G02B 13/24 for reproducing or copying at short object distances
• CPC Class Codes: G03F 7/70241 Optical aspects of refractive lens systems, i.e. comprising only refractive elements
• 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 7/70341 Details of immersion lithography aspects, e.g. exposure media or control of immersion liquid supply chemical composition of immersion liquids G03F7/2041

Abstract

A refractive projection optical system for imaging a first object into a region of a second object comprises a plurality of lenses disposed along an imaging beam path of the projection optical system; wherein the projection optical system is configured to have a numerical aperture on a side of the second object of greater than 1 wherein the projection optical system is configured to generate an intermediate image of the first object and to image the intermediate image into the region of the second object, wherein the intermediate image is formed in between, the first and second objects.

Claims

1. A refractive projection optical system for imaging a first object into a region of a second object, the projection optical system comprising:

a plurality of lenses disposed along an imaging beam path of the projection optical system;

wherein the projection optical system is configured to generate an intermediate image of the first object and to image the intermediate image into the region of the second object, wherein the intermediate image is formed in between the first and second objects.

2. The refractive projection optical system according to claim 1,

wherein the plurality of lenses is dividable into a plurality of non-overlapping groups of lenses, such that a total refractive power of each group of lenses is one of a negative refractive power and a positive refractive power,

wherein a first group of lenses has a positive refractive power,

wherein a second group of lenses has a positive refractive power and is disposed between the first group of lenses having the positive refractive power and the region of the second object;

and wherein the intermediate image is formed in a region between the first group of lenses having the positive refractive power and the second group of lenses having the positive refractive power.

3. The refractive projection optical system according to claim 2, wherein one third group of lenses having a negative refractive power is disposed in the region between the first group of lenses having the positive refractive power and the second group of lenses having the positive refractive power.

4. The refractive projection optical system according to claim 3, wherein a fourth group of lenses having a negative refractive power is disposed between the second group of lenses having the positive refractive power and the region of the second object, and wherein a fifth group of lenses having a positive refractive power is disposed between the fourth group of lenses having the negative refractive power and the region of the second object.

5. The refractive projection optical system according to claim 4, wherein the fifth group of lenses is that group of lenses among all groups of lenses disposed closest to the second object.

6. The refractive projection optical system according to claim 2, wherein a sixth group of lenses having a negative refractive power is disposed between the first group of lenses having the positive refractive power and the first object, and wherein a seventh group of lenses having a positive refractive power is disposed between the sixth group of lenses having the negative refractive power and the first object.

7. The refractive projection optical system according to claim 6, wherein an eighth group of lenses having a negative refractive power is disposed between the seventh group of lenses having the positive refractive power and the first object,

wherein an ninth group of lenses having a positive refractive power is disposed between the eighth group of lenses having the negative refractive power and the first object, and

wherein the ninth group of lenses is that group of lenses among all groups of lenses disposed closest to the first object.

8. The refractive projection optical system according to claim 1, wherein the projection optical system is configured to have a numerical aperture on a side of the second object of greater than 1.

9. The refractive projection optical system according to claim 1, wherein the refractive projection optical system is of an immersion type configured to have a liquid having a refractive index of greater than one provided in between of the second object and a front lens of the plurality of lenses disposed closest to the second object.

10. The refractive projection optical system according to claim 1, wherein an absolute value of a magnification of the imaging of the intermediate image into the region of the second object is less 0.5.

11. The refractive projection optical system according to claim 1, wherein an absolute value of a magnification of the imaging of the first object into the intermediate image is greater than 0.5.

12. The refractive projection optical system according to claim 1, wherein a ratio of a magnification of the imaging of the first object into the intermediate image over a magnification of the imaging of the intermediate image into the region of the second object is in a range of about 2 to 10.

13. The refractive projection optical system according to claim 1, wherein the imaging of the first object into the intermediate image is such that at least one of the following conditions is fulfilled:

an angle of at least one chief ray of the intermediate image is greater than 4°

;

a longitudinal spherical aberration of the intermediate image is greater than 0.8 mm;

an astigmatism value of the intermediate image is greater than 11.0 mm;

an aberration of the intermediate image is greater than 1.5%;

a RMS of a spot diameter on an optical axis of the projection optical system is greater than 0.5 mm;

a RMS of a spot diameter at a field point farthest away from the optical axis of the projection optical system is greater than 5 mm; and

a RMS deviation of a wavefront at the intermediate image is greater than 10λ

/NA, wherein λ

is a wavelength of imaging light and NA is a numerical aperture of the imaging at the intermediate image.

14. The refractive projection optical system according to claim 1, wherein the imaging of the first object into the second image is such that at least one of the following conditions is fulfilled:

an angle of at least one chief ray of the image is less than 1°

;

a longitudinal spherical aberration of the image is less than 0.001 mm;

an astigmatism value of the image is less than 100 nm;

an aberration of the image is less than 0.001%;

a RMS of a spot diameter on an optical axis of the projection optical system is less than 0.001 mm;

a RMS of a spot diameter at a field point farthest away from the optical axis of the projection optical system is less than 0.002 mm; and

a RMS deviation of a wave front is less than 0.1 times a diffraction limit.

15. The refractive projection optical system according to claim 1, wherein the system further comprises at least one substantially flat mirror disposed in the imaging beam path of the optical system, for folding the beam path to reduce a length of the system.

16. The refractive projection optical system according to claim 15, wherein the substantially flat mirror has a radius of curvature greater than 1,000 m.

17. The refractive projection optical system according to claim 1, wherein an effective diameter of each lens of the plurality of lenses is smaller than 250 mm.

18. The refractive projection optical system according to claim 1, wherein the optical system is free of a physical beam splitter.

19. The refractive projection optical system according to claim 1, wherein the intermediate image has a field curvature having a radius of curvature which is less than four times a free diameter of the intermediate image.

20. The refractive projection optical system according to claim 1, wherein the intermediate image is completely formed within a space between two adjacent lenses.

21. A projection exposure system, comprising:

an illumination optical system for generating an illumination beam of light;

a first mount for mounting a patterning structure as a first object within the illumination beam of light;

a second mount for mounting a radiation sensitive substrate as a second object; and

the refractive projection optical system according to one of claims 1 to 16 for imaging the first object into a region of the second object using a portion of the illumination beam of light traversing the patterning structure.

22. A method of manufacturing a microstructured device, comprising:

a first imaging of a patterning structure into an intermediate image of; and

a second imaging of the intermediate image of the patterning structure into a region of a radiation sensitive substrate for exposing the radiation sensitive substrate;

wherein the first imaging and the second imaging is performed by using a refractive projection optical system.

23. The method according to claim 22, wherein the first imaging comprises:

a first expanding of a cross section of an imaging beam downstream of the patterning structure;

a first reducing of the cross section of the imaging beam downstream of the first expanding of the cross section;

a second expanding of the cross section of the imaging beam downstream of the first reducing of the cross section;

a second reducing of the cross section of the imaging beam downstream of the second expanding of the cross section;

a third expanding of the cross section of the imaging beam downstream of the second reducing of the cross section; and

a third reducing of the cross section of the imaging beam downstream of the third expanding of the cross section.

24. The method according to claim 22, wherein the second imaging comprises:

a fourth expanding of the cross section of the imaging beam downstream of the intermediate image;

a fourth reducing of the cross section of the imaging beam downstream of the fourth expanding of the cross section;

a fifth expanding of the cross section of the imaging beam downstream of the fourth reducing of the cross section; and

a fifth reducing of the cross section of the imaging beam downstream of the fifth expanding of the cross section;

wherein the imaging beam is incident onto the radiation sensitive substrate downstream of the second reducing of the cross section.

25. The method according to claim 22, wherein the second imaging has a numerical aperture on a side of the radiation sensitive substrate of greater than 1.

26. The method according to claim 22, further comprising providing a liquid in a space between the radiation sensitive substrate and a lens of the refractive projection optical system closest to the radiation sensitive substrate.

27. The method according to claim 22, wherein the first imaging is performed such that at least one of the following conditions is fulfilled:

an angle of at least one chief ray of the intermediate image is greater than 4°

;

a longitudinal spherical aberration of the intermediate image is greater than 0.8 mm;

an astigmatism value of the intermediate image is greater than 11.0 mm;

an aberration of the intermediate image is greater than 1.5%;

a RMS of a spot diameter on an optical axis of the projection optical system is greater than 0.5 mm;

a RMS of a spot diameter at a field point farthest away from the optical axis of the projection optical system is greater than 5 mm; and

a RMS deviation of a wavefront at the intermediate image is greater than 10λ

/NA, wherein λ

is a wavelength of imaging light and NA is a numerical aperture of the imaging at the intermediate image.

28. The method according to claim 22, wherein the first imaging is performed such that at least one of the following conditions is fulfilled:

an angle of at least one chief ray of the image is less than 1°

;

a longitudinal spherical aberration of the image is less than 0.001 mm;

an astigmatism value of the image is less than 100 nm;

an aberration of the image is less than 0.001%;

a RMS of a spot diameter on an optical axis of the projection optical system is less than 0.001 mm;

a RMS of a spot diameter at a field point farthest away from the optical axis of the projection optical system is less than 0.002 mm; and

a RMS deviation of a wave front is less than 0.1 times a diffraction limit.

29. A microstructured device manufactured by the method according to claim 22.

30. A refractive projection optical system, comprising:

a compound lens system having

a first refractive image former for forming a real intermediate image, and

a second refractive image former, wherein said compound lens system is a micro-lithographic projection objective.