Method for producing an illumination system for an EUV projection exposure system, and illumination system

Patent metadata

Field	Value
Publication number	US-11048172-B2
Application number	US-201916704677-A
Country	US
Kind code	B2
Filing date	Dec 5, 2019
Priority date	Mar 10, 2016
Publication date	Jun 29, 2021
Grant date	Jun 29, 2021

Abstract

The disclosure relates to a method for producing an illumination system for an EUV apparatus in and to an illumination system for an EUV apparatus.

First claim

What is claimed is:

1. A method for producing an illumination system for an EUV apparatus, the illumination system being configured so that, during operation of the EUV apparatus, the illumination system receives EUV radiation of an EUV radiation source at a source position in an entrance plane and shapes, from a portion of the received EUV radiation, illumination radiation that is directed into an illumination field in an exit plane of the illumination system, the illumination field fulfilling an illumination specification, the method comprising:
installing mirror modules of the illumination system at installation positions provided for the mirror modules to establish an illumination beam path which extends from the source position to the illumination field, the mirror modules comprising a first mirror module comprising a first facet mirror at a first installation position and a second mirror module comprising a second facet mirror at a second installation position of the illumination system;
coupling measurement light into the illumination beam path at an input coupling position which corresponds to the source position so that the measurement light follows the illumination beam path from the source position to each of the mirror modules;
detecting measurement light after reflection of the measurement light at each of the mirror modules of the illumination beam path;
ascertaining current measurement values for at least one system measurement variable from detected measurement light, the current measurement values representing a current state of the system measurement variable of the illumination system;
ascertaining correction values from the current measurement values using sensitivities that represent a relationship between the system measurement variable and a change in the orientation of at least one mirror module in its installation position; and
adjusting at least one mirror module with variation of the orientation of the mirror module in the installation position in degrees of freedom of a rigid body using the correction values to change the current state in a manner such that in the case of irradiation with EUV radiation from the EUV radiation source, the illumination radiation in the illumination field fulfills the illumination specification.

2. The method of claim 1 , further comprising using measurement light from a different wavelength range than the EUV radiation used during use of the illumination system, wherein the wavelength range of the measurement light is selected from the group consisting of a visible spectral range, an adjoining UV spectral range, and an IR spectral range.

3. The method of claim 2 , further comprising ascertaining, from the current measurement values, a system measurement variable selected from the group consisting of:
(i) a position of the illumination field in the exit plane;
(ii) a local distribution of measurement light in a pupil plane, which is Fourier-transformed with respect to the exit plane, of the illumination system; and
(iii) a position of a measurement light spot on a facet of the second facet mirror.

4. The method of claim 2 , further comprising setting selected ray angles of the input measurement light into the illumination beam path during the input-coupling of measurement light separately measure individual illumination channels.

5. The method of claim 3 , further comprising:
for the ascertaining the position of the illumination field, defining at least two characteristic points at the periphery and/or within the illumination field;
determining a current position of the illumination field on the basis of the current positions of the characteristic points in a plane selected from the group consisting of the exit plane and a measurement plane that is conjugate to the exit plane; and
defining a desired position of the illumination field on the basis of the desired positions of the characteristic points.

6. The method of claim 3 , further comprising:
for ascertaining the local distribution of measurement light in the pupil plane which is Fourier-transformed with respect to the exit plane, defining a multiplicity of characteristic points in the pupil plane;
determining a current local distribution of the measurement light on the basis of the current positions of the characteristic points in a measurement plane which is Fourier-transformed with respect to the exit plane; and
defining a desired local distribution of the measurement light on the basis of the desired positions of the characteristic points.

7. The method of claim 3 , further comprising:
for ascertaining the position of a measurement light spot on a facet of the second facet mirror, displacing a position of the measurement light source relative to a desired position; and
capturing an intensity of a measurement light spot as a function of the extent of the displacement.

8. The method of claim 5 , further comprising, in an evaluation of the current measurement values, deriving a stipulation for a change in the orientation of at least one of the mirror modules from a position difference between the current positions and the associated desired positions of the characteristic points.

9. The method of claim 6 , further comprising, in an evaluation of the current measurement values, deriving a stipulation for a change in the orientation of at least one of the mirror modules from a position difference between the current positions and the associated desired positions of the characteristic points.

10. The method of claim 1 , wherein the first mirror module is upstream of the second mirror module along the illumination beam path.

11. The method of claim 1 , further comprising:
demounting the first mirror module from its installation position;
removing the first mirror module from the illumination system;
installing a third mirror module in place of the first mirror module into the installation position; and
adjusting the third mirror module by changing an orientation of the mirror module in the installation position in degrees of freedom of a rigid body.

12. The method of claim 11 , further comprising modifying the first mirror module to provide the third mirror module.

13. The method of claim 11 , further comprising:
before demounting the first mirror module, performing a reference measurement using the measurement system in order to capture a reference state that represents the adjustment state before the start of the swap operation; and
after adjusting the third mirror module, measuring the adjustment state measured compared to the reference state to restore the adjustment state from before the swap operation.

14. An illumination system for an EUV apparatus, the illumination system being configured so that, during operation of the EUV apparatus, the illumination system receives EUV radiation of an EUV radiation source at a source position in an entrance plane and shapes, from at least one portion of the received EUV radiation, illumination radiation that is directed into an illumination field in an exit plane of the illumination system, the illumination field fulfilling an illumination specification, the illumination system comprising:
a plurality of mirror modules installed at installation positions of the illumination system provided for the mirror modules and configured to define an illumination beam path which extends from the source position to the illumination field, the mirror modules comprising a first mirror module comprising a first facet mirror at a first installation position and a second mirror module comprising a second facet mirror at a second installation position of the illumination system; a

Assignees

• Zeiss Carl Smt Gmbh

Inventors

• Baier Juergen
• Runde Daniel
• Manger Matthias
• Mueller Ulrich
• Lichtenthaeler Joerg
• Orthen André
• Welker Joachim
• Holz Markus
• Holderer Hubert

Classifications

• G03F7/70033 Primary

  by plasma extreme ultraviolet [EUV] sources · CPC title

• G03F7/70141 Primary

  Illumination system adjustment, e.g. adjustments during exposure or alignment during assembly of illumination system · CPC title

• G03F7/702

  Reflective illumination, i.e. reflective optical elements other than folding mirrors, e.g. extreme ultraviolet [EUV] illumination systems · CPC title

• G03F7/70158 Primary

  Diffractive optical elements · 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