Optical system, in particular of a microlithographic projection exposure apparatus

Patent metadata

Field	Value
Publication number	US-9588433-B2
Application number	US-201414501770-A
Country	US
Kind code	B2
Filing date	Sep 30, 2014
Priority date	Apr 17, 2012
Publication date	Mar 7, 2017
Grant date	Mar 7, 2017

Abstract

The invention relates to an optical system, in particular of a microlithographic projection exposure apparatus, with an optical system axis (OA) and a polarization-influencing optical arrangement. According to one aspect, the polarization-influencing optical arrangement comprises at least one polarization-influencing optical element, which has a monolithic design and linear birefringence, wherein the overall absolute value of the birefringence of all of the polarization-influencing optical elements deviates by at most ±15% from the value lambda/2, wherein lambda is the working wavelength of the optical system, wherein the direction of the fast axis of this birefringence varies in a plane perpendicular to the optical system axis (OA) in the at least one polarization-influencing optical element, and wherein the distribution of the fast axis of the birefringence of the polarization-influencing optical element is brought about by radiation-induced defects, which are situated in at least one optically unused region of the element.

First claim

The invention claimed is:

1. An optical system having an optical system axis, the optical system comprising:
a polarization-influencing optical arrangement comprising at least one polarization-influencing optical element having a monolithic design and linear birefringence,
wherein:
lambda is a working wavelength of the optical system;
an overall absolute value of birefringence of all of the at least one polarization-influencing optical element deviates by at most ±15% from lambda/2;
a direction of a fast axis of the birefringence of the at least one polarization-influencing optical element varies in a plane perpendicular to the optical system axis;
a distribution of the fast axis of the birefringence of the at least one polarization-influencing optical element is due to radiation-induced defects situated in at least one optically unused region of the at least one polarization-influencing optical element;
the optically unused region of the at least one polarization-influencing optical element has an annular geometry; and
the optical system is a microlithographic optical system.

2. The optical system of claim 1 , wherein the overall absolute value of the birefringence of all the at least one polarization-influencing optical element deviates by at most ±10% from lambda/2.

3. The optical system of claim 1 , wherein, during the operation of the optical system, the polarization-influencing optical arrangement converts a constant linear input polarization distribution of light incident on the arrangement into a distribution selected from the group consisting of an at least approximately tangential distribution, an at least approximately radial distribution, and a mixed radial/tangential output polarization distribution.

4. The optical system of claim 1 , wherein the distribution of the fast axis of the birefringence of the at least one polarization-influencing optical element is due to radiation-induced defects in: a) a first radially inner region with respect to the optical system axis; and b) a second radially outer region with respect to the optical system axis.

5. The optical system of claim 1 , wherein the at least one polarization-influencing optical element has a plane-parallel geometry.

6. The optical system of claim 1 , wherein the at least one polarization-influencing optical element comprises an amorphous material.

7. The optical system of claim 1 , wherein the at least one polarization-influencing optical element comprises quartz glass (SiO 2 ).

8. The optical system of claim 1 , further comprising a lambda/4 plate upstream of the polarization-influencing optical arrangement along a direction of light propagation through the optical system during use of the optical system.

9. The optical system of claim 1 , further comprising a rotator downstream of the at least one polarization-influencing optical arrangement along a direction of light propagation through the optical system during use of the optical system, wherein during use of the optical system the rotator causes a rotation of the polarization direction of incident light about a polarization rotation angle of 45°.

10. The optical system of claim 1 , further comprising a rotator, wherein during use of the optical system the rotator causes a rotation of the polarization direction of incident light about a polarization rotation angle of 90°.

11. The optical system of claim 10 , wherein the polarization-influencing optical arrangement comprises a plurality of polarization-influencing optical elements in succession along a direction of light propagation through the optical system during use of the optical system.

12. The optical system of claim 11 , wherein at least one of the polarization-influencing optical elements is both upstream of the rotator along the direction and downstream of the rotator along the direction.

13. The optical system of claim 10 , wherein during use of the optical system a system retardation generated in the optical system upstream of the rotator along the direction is at least partly compensated for by a system retardation generated in the optical system downstream of the rotator along the direction.

14. The optical system of claim 1 , further comprising an actuator device configured to independently move an element of the optical system.

15. The optical system of claim 14 , wherein the element comprises a member selected from the group consisting of a lambda/4 plate, a 45° rotator and a 90° rotator.

16. The optical system of claim 14 , further comprising a lambda/4 plate, a 45° rotator and a 90° rotator, wherein:
the actuator device is configured to independently move the lambda/4 plate from inside an optical beam path of the optical system to outside the optical beam path of the optical system;
the actuator device is configured to independently move the 45° rotator from inside the optical beam path of the optical system to outside the optical beam path of the optical system; and
the actuator device is configured to independently move the 90° rotator from inside the optical beam path of the optical system to outside the optical beam path of the optical system.

17. The optical system of claim 1 , wherein the polarization-influencing optical arrangement comprises a plurality of polarization-influencing optical elements in succession along a direction of light propagation through the optical system during use of the optical system.

18. An apparatus, comprising:
an illumination device; and
a projection lens,
wherein:
the apparatus is a microlithographic projection exposure apparatus; and
the illumination device comprises an optical system according to claim, and/or the projection lens comprises an optical system according to claim 1 .

19. A method of using a projection exposure apparatus comprising an illumination system and a projection optical unit, the method comprising:
using the illumination system to illuminate at least a part of reticle; and
using the projection optical unit to project at least part of the illumination part of the reticle onto a wafer,
wherein the illumination system comprises an optical system according to claim 1 .

20. An optical system having an optical system axis, the optical system comprising:
a polarization-influencing optical arrangement comprising at least one polarization-influencing optical element having a monolithic design and linear birefringence,
wherein:
a direction of a fast axis of the birefringence of the at least one polarization-influencing optical element varies in a plane perpendicular to the optical system axis;
a distribution of the fast axis of the birefringence of the at least one polarization-influencing optical element is due to radiation-induced defects situated in at least one optically unused region of the at least one polarization-influencing optical element;
the optically unused region of the at least one polarization-influencing optical element has an annular geometry;
during use of the optical system, the at least one polarization-influencing optical element converts a constant linear input polarization distribution of light incident on the polarization-influencing optical arrangement into a distribution selected from the group consisting of an at least approximately tangential distribution, an at least approximately radial distribution, and a mixed radial/tangential output polarization distribution; and
the optical system is a microlithographic optical system.

21. An optical system having an optical system axis, the optical syste

Assignees

• Zeiss Carl Smt Gmbh

Inventors

• Saenger Ingo

Classifications

• G02B5/3083

  Birefringent or phase retarding elements (G02B5/3008, G02B5/3016 take precedence; systems for polarisation control G02B27/286; manufacturing phase modulating patterns by lithographic processes G03F7/001) · CPC title

• G03F7/70966

  Birefringence · CPC title

• G02B27/286

  for controlling or changing the state of polarisation, e.g. transforming one polarisation state into another (G02B5/3083 takes precedence; light guide coupling means utilising polarising elements G02B6/34) · CPC title

• G03F7/70191 Primary

  Optical correction elements, filters or phase plates for controlling intensity, wavelength, polarisation, phase or the like · CPC title

• G02B5/3075 Primary

  for use in the UV (G02B5/3066 takes precedence) · CPC title