Projection exposure methods and apparatus, and projection optical systems

• US 6,864,961 B2
• Filed: 04/04/2003
• Issued: 03/08/2005
• Est. Priority Date: 09/29/1999
• Status: Expired due to Term

• Current Assignee: Nikon Corporation
• Original Assignee: Nikon Corporation
• Inventors: Omura, Yasuhiro
• Primary Examiner(s): NGUYEN, HUNG
• Application Number:
  US10/406,223
• Publication Number:
  US 20030206282A1
• Time in Patent Office: 704 Days
• Field of Search: 355/53, 355/55, 355 67- 71, 359618-620, 359/758, 359/770
• US Class Current: 355/67
• CPC Class Codes: G02B 13/143 for use with ultraviolet radiation
• CPC Class Codes: G02B 13/18 with lenses having one or more non-spherical faces, e.g. for reducing geometrical aberration G02B13/002 takes precedence
• 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 7/70741 Handling masks outside exposure position, e.g. reticle libraries
• CPC Class Codes: G03F 7/70883 of optical system
• CPC Class Codes: G03F 7/70958 Optical materials or coatings, e.g. with particular transmittance, reflectance or anti-reflection properties

Abstract

Provided is a dioptric projection optical system favorably applicable to projection exposure apparatus used in the lithography step in fabrication of microdevices such as semiconductor devices. This projection optical system includes a positive, front lens unit (GF), an aperture stop (AS), and a positive, rear lens unit (GR) and is a bitelecentric optical system. The optical system satisfies the following condition:
0.065<f2/L<0.125,

• • where f2 is a focal length of the rear lens unit (GR) and L is a distance between an object and an image.

The projection optical system includes at least one aspheric surface (ASP 1 to ASP 6).

Claims

1. A projection optical system for forming a reduced image of a pattern on a first surface, onto a second surface, comprising, in order from the first surface side:

a first lens unit having a negative refracting power;

a second lens unit having a positive refracting power;

a third lens unit having a negative refracting power;

a fourth lens unit having a positive refracting power;

an aperture stop; and

a fifth lens unit having a positive refracting power;

wherein the following conditions are satisfied;

−

1.3<

1/β

1<

0, and

0.08<

L1/L<

0.17,

where β

1 is a composite, lateral magnification of said first lens unit and said second lens unit, L1 is a distance from said first surface to a lens surface closest to said second surface in said second lens unit, and L is a distance from said first surface to said second surface.

2. The projection optical system according to claim 1, wherein when six lenses are selected in order from the said first surface side of lenses having their respective refracting powers in said projection optical system, at least one surface of the six lenses has an aspheric shape with a negative refracting power.

3. The projection optical system according to claim 1, wherein said first and second lens units include at least two aspheric lens surfaces and comprise ten or more lenses.

4. The projection optical system according to claim 1, wherein the following condition is satisfied:

0.46<

C/L<

0.64,

where C is a total thickness along the optical axis of the radiation-transmitting refractors located in the optical path of said projection optical system and L is the distance from said first surface to said second surface.

5. The projection optical system according to claim 1, wherein the following condition is satisfied:

0.15<

Ea/E<

0.7,

where E is the total number of members having their respective refracting powers among the radiation-transmitting refractors in said projection optical system and Ea is the total number of members each provided with a lens surface of aspheric shape.

6. The projection optical system according to claim 5, wherein the total number of said members having their respective refracting powers is not less than 16.

7. The projection optical system according to claim 5, wherein the total number of said members having their respective refracting powers is not more than 26.

8. The projection optical system according to claim 5, wherein the radiation-transmitting refractors in said projection optical system are made of a single kind of material.

9. The projection optical system according to claim 5, wherein the radiation-transmitting refractors in said projection optical system comprise first radiation-transmitting refractors made of a first material and second radiation-transmitting refractors made of a second material, and

wherein a percentage of the number of said second radiation-transmitting refractors to the number of the members having their respective refracting powers among said radiation-transmitting refractors, is not more than 32%.

10. The projection optical system according to claim 1, wherein when a ray parallel to the optical axis of said projection optical system is made incident from said second surface side into said projection optical system, an angle between said optical axis and said ray as emitted toward said first surface, is not more than 50 minutes.

11. The projection optical system according to claim 1, wherein the following condition is satisfied:

0.065<

f2/L<

0.125,

wherein f2 is a focal length of said fifth lens unit and L is the distance from said first surface to said second surface.

12. A method of fabricating a projection optical system for forming a reduced image of a pattern on a first surface, onto a second surface, comprising the steps of:

a step of preparing a first lens unit having a negative refracting power;

a step of preparing a second lens unit having a positive refracting power;

a step of preparing a third lens unit having a negative refracting power;

a step of preparing a fourth lens unit having a positive refracting power;

a step of preparing an aperture stop;

a step of preparing a fifth lens unit having a positive refracting power; and

a step of locating said first lens unit, said second lens unit, said third lens unit, said fourth lens unit, said aperture stop, and said fifth lens unit in the order named from the said first surface side;

wherein, where β

1 is a composite, lateral magnification of said first lens unit and said second lens unit, L1 a distance from said first surface to a lens surface closest to said second surface in said second lens unit, and L a distance from said first surface to said second surface, said first and second lens units are prepared so as to satisfy the following condition;

−

1.3<

1/β

1<

0,

and said first and second lens units are located so as to satisfy the following condition;

0.08<

L1/L<

0.17.

13. A dioptric projection optical system for forming an image of a first surface onto a second surface, comprising:

a first lens group with a negative refractive power, arranged in an optical path between the first surface and the second surface;

a second lens group with a positive refractive power, arranged in an optical path between the first lens group and the second surface;

a third lens group with a negative refractive power, arranged in an optical path between the second lens group and the second surface;

a fourth lens group with a positive refractive power, arranged in an optical path between the third lens group and the second surface;

an aperture stop arranged in an optical path between the fourth lens group and the second surface; and

a fifth lens group with a positive refractive power, arranged in an optical path between the aperture stop and the second surface,

wherein lenses of the projection optical system have a clear aperture diameter respectively,

wherein said clear aperture diameters have a first relatively large value in the second lens group, a minimum value in the third lens group, and a second relatively large value in the third, fourth, or fifth lens groups, and

wherein the minimum value of the clear aperture diameters is the only waist in the optical path between the first surface and the second surface.

14. A method of imaging an image of a first surface onto a second surface, comprising the steps of:

guiding a radiation from the first surface to a first lens group with a negative refractive power;

guiding a radiation from the first lens group to a second lens group with a positive refractive power;

guiding a radiation from the second lens group to a third lens group with a negative refractive power;

guiding a radiation from the third lens group to a fourth lens group with a positive refractive power;

guiding a radiation from the fourth lens group to an aperture stop;

guiding a radiation from the aperture stop to a fifth lens group with a positive refractive power; and

imaging the image of the first surface onto the second surface based on a radiation from the fifth lens group,

wherein a diameter of the radiation from the first surface toward the second surface has a first relatively large value in the second lens group, a minimum value in the third lens group, and a second relatively large value in the third, fourth, or fifth lens groups, and

wherein the minimum value of the diameter is the only waist in the optical path between the first surface and the second surface.

15. A dioptric projection optical system for forming an image of a first surface onto a second surface, comprising:

a first lens group with a negative refractive power, arranged in an optical path between the first surface and the second surface;

a second lens group with a positive refractive power, arranged in an optical path between the first lens group and the second surface;

a third lens group with a negative refractive power, arranged in an optical path between the second lens group and the second surface;

a fourth lens group with a positive refractive power, arranged in an optical path between the third lens group and the second surface;

an aperture stop arranged in an optical path between the fourth lens group and the second surface; and

a fifth lens group with a positive refractive power, arranged in an optical path between the aperture stop and the second surface,

wherein lenses of the projection optical system have an outer diameter respectively,

wherein the outer diameters have a first relatively large value in the second lens group, a minimum value in the third lens group, and a second relatively large value in the third, fourth, or fifth lens groups, and

wherein the minimum value of the outer diameters is the only waist in the optical path between the first surface and the second surface.