Apparatus and method for compensating a defect of a channel of a microlithographic projection exposure system

Patent metadata

Field	Value
Publication number	US-9632413-B2
Application number	US-201414466053-A
Country	US
Kind code	B2
Filing date	Aug 22, 2014
Priority date	Mar 29, 2012
Publication date	Apr 25, 2017
Grant date	Apr 25, 2017

Abstract

The invention relates to an illumination system of a microlithographic projection exposure apparatus comprising (a) a plurality of channels, each channel guiding a partial beam and at least one channel comprising at least one defect, and (b) at least one optical element arranged within the at least one channel having the at least one defect, the optical element being adapted to at least partially compensate the at least one defect of the partial beam of the channel.

First claim

The invention claimed is:

1. An illumination system configured so that, during use of the illumination system, the illumination system guides a plurality of partial beams of light, each partial beam of light having a corresponding channel, the illumination system comprising:
an optical element,
wherein:
the optical element comprises local persistent modifications in an area of the optical element outside an optically relevant area of the optical element;
the local persistent modifications in the optical element produce a strain-induced birefringence in the optical element;
the optical element is configured so that, during use of the illumination system;
a) the partial beam of light in a first channel impinges on the optical element; and
b) the strain-induced birefringence of the optical element at least partially compensates a variation of a polarization of the partial beam of light of the first channel; and

the illumination system is a microlithographic illumination system.

2. The illumination system of claim 1 , wherein the optical element is configured so that, during use of the illumination system, the optical element modifies the polarization of the partial beam of light of the first channel.

3. The illumination system of claim 1 , further comprising a mirror array comprising a first mirror, wherein the first mirror is configured so that, during use of the illumination system, the first mirror directs a partial beam passing through the optical element in an outer edge of a pupil in agreement with a predetermined target pupil.

4. The illumination system of claim 1 , wherein the strain induced birefringence of the optical element comprises a fast axis having a fixed direction.

5. The illumination system of claim 1 , wherein the strain induced birefringence of the optical element comprises a retardation of from one nanometer to 10 nanometers in the optically relevant area of the optical element.

6. The illumination system of claim 5 , wherein the optical element is configured so that, during use of the illumination system, the optical element maximizes a modification of the polarization of the partial beam of light of the first channel based on an orientation of a fast axis of the optical element with respect to the polarization of the partial beam of light of the first channel.

7. The illumination system of claim 1 , wherein:
the illumination system comprises a two dimensional mirror array comprising a plurality of mirrors; and
each mirror of the plurality of mirrors of the two dimensional mirror array is tiltable about two axes so that, during use of the illumination system, the partial beams of light of the first channel is superimposed with a partial beam of light of second channel in a single spot so that a retardation of the superimposed partial beams of light compensates retardation of the illumination system.

8. The illumination system of claim 7 , wherein, during use of the illumination system, the polarization of the partial beam of light of the first channel is rotated with respect to the polarization of the partial beam of light of the second channel.

9. The illumination system of claim 1 , wherein, during use of the illumination system, compensating the variation of the polarization of the partial beam of light of the first channel increases an intensity in preferred state of a beam exiting the illumination system.

10. The illumination system of claim 1 , wherein the optical element comprises an actuator configured to induce strain in the optically relevant area of the optical element.

11. The illumination system of claim 1 , wherein, during use of the illumination system, the optical element is dynamically insertable in the first channel.

12. The illumination system of claim 1 , wherein the optical element comprises a multitude of optical elements having different fixed fast axes and/or different amounts of retardations.

13. The illumination system of claim 12 , wherein the multitude of optical elements is configured so that, during use of the illumination system, the multitude of optical elements is insertable in a multitude of the channels, each one having a defect so that an intensity in a preferred state of the beam exiting the illumination system is maximized.

14. The illumination system of claim 1 , wherein the optical element comprises a polarizer configured to change a polarization of the partial beam of light of the first channel.

15. The illumination system of claim 1 , wherein the at least one optical element comprises a mirror for reflecting the partial beam.

16. The illumination system of claim 1 , wherein the at least one optical element comprises a lens for deflecting the partial beam.

17. The illumination system of claim 1 , wherein the optical element comprises a plate, the plate has a first optically relevant area for the first channel, the plate has a second optically relevant area for a second channel, and the first and second optically relevant areas are between areas of the plate which are optically not relevant.

18. The illumination system of claim 17 , wherein the first and second optically relevant areas:
are arranged in a one-dimensional row or are arranged in a two-dimensional rectangular matrix;
have a diameter which is adjustable to a diameter of the partial beams of the first and second channels; and
have a distance which is adjustable to a distance between the partial beam of light each of the first and second channels.

19. The illumination system of claim 17 , wherein the plate comprises at least two optically relevant areas configured to compensate at least two different defects.

20. The illumination system of claim 17 , wherein the first and second optically relevant areas of the plate comprise a polarizer configured to change a polarization of the partial beam of each of the first and second channels.

21. The illumination system of claim 17 , wherein the plate is moveable essentially perpendicular to directions of the partial beams of light of the first and second channels, and/or the plate is rotatable essentially perpendicular to directions of the partial beams of light of the first and second channels.

22. The illumination system of claim 17 , wherein, during use of the illumination system, the plate is dynamically insertable in a beam path of the partial beams of the first and second channels.

23. The illumination system of claim 1 , wherein the illumination system is configured so that, during use of the illumination system, ultra-short laser pulses introduce the local persistent modifications of the optical element.

24. An apparatus, comprising:
an illumination system according to claim 1 ; and
a projection objective,
wherein the apparatus is a microlithographic projection exposure apparatus.

25. A method comprising:
using an illumination system of claim 1 to illuminate a mask; and
using a projection objective to image at least a portion of the mask onto a photosensitive material.

26. The method of claim 25 , further comprising using the first optical element to compensate for the variation of the polarization of the partial beam of light of the first channel.

27. The method of claim 26 , further comprising inserting the optical element into the first channel.

28. The illumination system of claim 1 , wherein a local persistent modification of the optical element is a local modifi

Assignees

• Zeiss Carl Smt Gmbh

Inventors

• Saenger Ingo
• Schlesener Frank

Classifications

• G03F7/70116 Primary

  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

• G03F7/70191

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

• 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

• G03F7/2006 Primary

  using coherent light; using polarised light · CPC title