Illumination system for an EUV projection lithographic projection exposure apparatus

Patent metadata

Field	Value
Publication number	US-9851641-B2
Application number	US-201514594466-A
Country	US
Kind code	B2
Filing date	Jan 12, 2015
Priority date	Aug 8, 2012
Publication date	Dec 26, 2017
Grant date	Dec 26, 2017

Abstract

An illumination system for an EUV projection lithographic projection exposure apparatus comprises an EUV light source, which generates an output beam of EUV illumination light with a predetermined polarization state. An illumination optical unit guides the output beam along an optical axis, as a result of which an illumination field in a reticle plane is illuminated by the output beam. The light source comprises an electron beam supply device, an EUV generating device and a polarization setting device. The EUV generating device is supplied with an electron beam by the electron beam supply device. The polarization setting device exerts an adjustable deflecting effect on the electron beam for setting the polarization of the output beam. This results in an illumination system, which operates on the basis of an electron beam-based EUV light source and provides an output beam, which is improved for a resolution-optimized illumination.

First claim

The invention claimed is:

1. An illumination system, comprising:
a free electron laser configured to generate an EUV radiation beam, the free electron laser comprising:
a first device configured to generate an electron beam;
a second device configured to interact with the electron beam to generate EUV radiation; and
a third device configured to exert an adjustable deflecting effect on the electron beam to set a polarization of the EUV radiation beam;

a scanning device configured to deflect the EUV radiation beam; and
an illumination optical unit configured to guide the EUV radiation beam along an optical axis to an illumination field,
wherein the scanning device is configured to: a) operate in a synchronized fashion with the third device; and b) match an aperture angle of the EUV radiation beam to the illumination optical unit.

2. The illumination system of claim 1 , wherein the second device comprises an undulator comprising deflection magnets, and the third device is configured to influence an effect of the deflection magnets on the electron beam.

3. The illumination system of claim 1 , wherein the second device comprises an undulator comprising deflection electromagnets, and the third device is configured to control an intensity of a current flow through the electromagnets.

4. The illumination system of claim 1 , wherein the illumination optical unit comprises:
a field facet mirror comprising a plurality of field facet; and
a pupil facet mirror comprising a plurality of pupil facets,

wherein:
the field and pupil facet mirrors are configured so that, during use of the illumination system, an illumination channel of EUV radiation is present between a field facet of a group of field facets and a pupil facet; and
the scanning device and the third device are associated by a tilt angle which is matched so that the EUV radiation beam has a predetermined polarization state on each of the pupil facets.

5. The illumination system of claim 4 , wherein the scanning device and the second device are associated by a tilt angle so that the polarization state of the EUV radiation beam on each of the pupil facets has a linear polarization component which is perpendicular on a connecting line from the pupil facet to a center of an arrangement of the pupil facets on the pupil facet mirror.

6. The illumination system of claim 4 , wherein the polarization state on the impinged upon pupil facets contains a polarization lead which takes account of subsequent influencing of the polarization along the path of the EUV radiation beam after the pupil facet mirror.

7. The illumination system of claim 4 wherein the matching is such that a plurality of pupil facets, between which no difference in the polarization state is prescribed, are impinged upon in sequence on the pupil facet mirror.

8. An optical system, comprising:
an illumination system according to claim 1 ; and
a projection optical unit configured to image the illumination field into an image field.

9. An apparatus, comprising:
an illumination system according to claim 1 ; and
a projection optical unit configured to image the illumination field into an image field;
a first object holder configured to hold an object in the illumination plane; and
a second object holder configured to hold a second object in an image plane which contains the image field,
wherein the apparatus is an EUV lithographic projection exposure apparatus.

10. A method of operating an EUV lithographic projection exposure apparatus which comprises an illumination system and a projection optical unit, the method comprising:
using the illumination system to illuminate a reticle in an illumination field of the illumination system; and
using projection optical unit to image at least a portion of the illuminated reticle onto a light-sensitive material in an image field of the projection optical unit,
wherein the illumination system is an illumination system according to claim 1 .

11. The illumination system of claim 1 , wherein:
the second device comprises an undulator comprising deflection electromagnets;
the third device is configured so that, during use of the illumination system, the third device controls an intensity of a current flow through the deflection electromagnets to adjust a deflecting effect of the second device on the electron beam to set a polarization of the EUV radiation beam.

12. The illumination system of claim 1 , wherein:
the second device comprises an undulator comprising deflection magnets; and
the third device is configured so that, during use of the illumination system, the third device influences the deflection magnets to influence a deflecting effect of the deflection magnets on the electron beam.

13. An illumination system, comprising:
a free electron laser configured to generate an EUV radiation beam, the free electron laser comprising:
a first device configured to generate an electron beam;
a second device configured to interact with the electron beam to generate EUV radiation; and
a third device configured to exert an adjustable deflecting effect on the electron beam to set a polarization of the EUV radiation beam;

a scanning device configured to deflect the EUV radiation beam; and
an illumination optical unit configured to guide the EUV radiation beam along an optical axis to an illumination field,
wherein the scanning device is configured to operate in a synchronized fashion with the third device, and the scanning device is arranged in an intermediate focus plane of the illumination optical unit.

Assignees

• Zeiss Carl Smt Gmbh

Inventors

• Patra Michael

Classifications

• G03F7/70116

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

• B82Y10/00

  Nanotechnology for information processing, storage or transmission, e.g. quantum computing or single electron logic · CPC title

• G03F7/70075

  Homogenization of illumination intensity in the mask plane by using an integrator, e.g. fly's eye lens, facet mirror or glass rod, by using a diffusing optical element or by beam deflection · CPC title

• H01S3/0903

  Free-electron laser · CPC title

• G21K1/067

  using surface reflection, e.g. grazing incidence mirrors, gratings (multilayer mirrors G21K1/062) · CPC title