Optical system of a microlithographic projection exposure apparatus, and microlithographic exposure

Patent metadata

Field	Value
Publication number	US-9500956-B2
Application number	US-201314143878-A
Country	US
Kind code	B2
Filing date	Dec 30, 2013
Priority date	Jul 26, 2011
Publication date	Nov 22, 2016
Grant date	Nov 22, 2016

Abstract

The disclosure relates to optical systems of a microlithographic projection exposure apparatus, and to a microlithographic exposure method. According to an aspect of the disclosure, an optical system has a light source, a ray-splitting optical element, which splits a light ray incident on this element when the projection exposure apparatus is in operation into a first partial ray and a second partial ray, with the first and the second partial ray having mutually orthogonal polarization directions, and at least one ray-deflecting optical element for generating a desired polarized illumination setting from the first partial ray and the second partial ray, wherein the ray-splitting optical element is arranged such that light incident on this ray-splitting optical element when the projection exposure apparatus is in operation has a degree of polarization of less than one.

First claim

The invention claimed is:

1. An optical system, comprising:
a first element configured so that, during use of the optical system, the first element splits a light ray incident on the first element into first and second partial rays, the first partial ray having a polarization direction which is orthogonal to a polarization direction of the second partial ray;
a second element configured so that, during use of the optical system, the second optical element generates a polarized illumination setting from the first and second partial rays;
a first arrangement comprising a plurality of first facets and a plurality of second facets, the first facets and second facets configured so that, during use of the optical system, the first and second facets are assigned different polarization states of the light reflected at the respective facets; and
a second arrangement comprising a plurality of third facets configured to that, during use of the optical system, the third facets are downstream of the first and second facets in a propagation direction of the light through the optical system,
wherein:
the first element is arranged so that, during use of the optical system, light incident on the first element has a degree of polarization of less than one;
for each of the third facets:
the third facet is switchable between first and second positions;
during use of the optical system when the third facet is in the first position, the third facet captures light from a first facet; and
during use of the optical system when the third facet is in the second position, the third facet captures light from a second facet;

the optical system has a pupil plane;
the optical system is configured so that, during use of the optical system, adjacent illumination spots in the pupil plane have polarization states that are different from each other; and
the optical system is a microlithographic optical system.

2. The optical system of claim 1 , wherein the first element is arranged so that, during use of the optical system, the degree of polarization of the light incident on the first element is less than 0.5.

3. The optical system of claim 1 , wherein the polarized illumination setting has a quasi-tangential polarization distribution.

4. The optical system of claim 1 , wherein the polarized illumination setting is a quadrupole illumination setting or a dipole illumination setting.

5. The optical system of claim 1 , further comprising a light source configured to generate the light.

6. The optical system of claim 5 , wherein the light is unpolarized light.

7. The optical system of claim 5 , wherein the light source is an EUV plasma source.

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

9. A method of using an apparatus comprising an illumination device and a projection lens, the method comprising:
using the illumination device to illuminate an object plane of the projection lens; and
using the projection lens to project the object plane into an image plane,
wherein the illumination device comprises the optical system of claim 1 .

10. The optical system of claim 1 , wherein the optical system is configured so that, during use of the optical system, all illumination spots in the pupil plane comprise polarized light.

11. An optical system, comprising:
a first light source configured to generate polarized light;
a second light source configured to generate polarized light;
a first arrangement comprising a plurality of first facets and a plurality of second facets, the first facets and second facets configured so that, during use of the optical system, the first and second facets are assigned different polarization states of light reflected at the respective facets; and
a second arrangement comprising a plurality of third facets configured so that, during use of the optical system, the third facets are arranged downstream of the first and second facets in a propagation direction of the light through the optical system,
wherein:
the optical system is a microlithographic optical system;
the optical system is configured so that during use of the optical system:
polarized light from the first light source impinges on the first facets; and
the polarized light from the second light source impinges on the second facets; and

for each of the third facets:
the third facet is switchable between first and second positions;
during use of the optical system when the third facet is in the first position, the third facet captures light from a first facet; and
during use of the optical system when the third facet is in the second position, the third facet captures light from a second facet.

12. The optical system of claim 11 , wherein the optical system comprises first and second field facet mirrors, wherein the first field facet mirror comprises the first facets, and the second field facet mirror comprises the second facets.

13. The optical system of claim 11 , wherein the optical system comprises a pupil facet mirror, and the pupil facet mirror comprises the third facets.

14. The optical system of claim 11 , wherein the different polarization states are orthogonal with respect to one another.

15. The optical system of claim 11 , wherein the optical system is configured so that, during use of the optical system, each of polarization state is generated via a reflection at a reflective element at the Brewster angle.

16. An apparatus, comprising:
an illumination device comprising an optical system according to claim 11 ; and
a projection lens,
wherein the apparatus is a microlithographic projection exposure apparatus.

17. A method of using an apparatus comprising an illumination device and a projection lens, the method comprising:
using the illumination device to illuminate an object plane of the projection lens; and
using the projection lens to project the object plane into an image plane,
wherein the illumination device comprises the optical system of claim 11 .

18. The optical system of claim 11 , wherein the optical system is configured so that, during use of the optical system:
the polarized light from the second light source does not impinge on the first facets; and
the polarized light from the first light source does not impinge on the second facets.

Assignees

• Zeiss Carl Smt Gmbh

Inventors

• Saenger Ingo
• Zimmermann Joerg
• Ruoff Johannes
• Meier Martin
• Schlesener Frank
• Hennerkes Christoph

Classifications

• G02B27/283

  used for beam splitting or combining · CPC title

• G03F7/70108 Primary

  Off-axis setting using a light-guiding element, e.g. diffractive optical elements [DOEs] or light guides · CPC title

• G03F7/70191 Primary

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

• G03F7/70116

  Off-axis setting using a programmable means, e.g. liquid crystal display [LCD], digital micromirror device [DMD] or pupil facets · CPC title

• G03F7/70566

  Polarisation control · CPC title