Method and device for characterizing a mask for microlithography

Patent metadata

Field	Value
Publication number	US-10698318-B2
Application number	US-201816026675-A
Country	US
Kind code	B2
Filing date	Jul 3, 2018
Priority date	Jul 7, 2017
Publication date	Jun 30, 2020
Grant date	Jun 30, 2020

Abstract

The invention relates to a method and a device for characterizing a mask for microlithography. In a method according to the invention, structures of a mask intended for use in a lithography process in a microlithographic projection exposure apparatus are illuminated by an illumination optical unit, wherein the mask is imaged onto a detector unit by an imaging optical unit, wherein image data recorded by the detector unit are evaluated in an evaluation unit. In this case, for emulating an illumination setting predefined for the lithography process in the microlithographic projection exposure apparatus, the imaging of the mask onto the detector unit is carried out in a plurality of individual imagings which differ from one another with regard to the illumination setting set in the illumination optical unit or the polarization-influencing effect set in the imaging optical unit.

First claim

What is claimed is:

1. A method for characterizing a mask for microlithography, comprising:
illuminating structures of a mask intended for use in a lithography process in a microlithographic projection exposure apparatus by an illumination optical unit;
imaging the mask onto a detector unit by an imaging optical unit;
evaluating image data recorded by the detector unit in an evaluation unit; and
emulating a predefined illumination setting that has a quasi-tangential polarization distribution for the lithography process in the microlithographic projection exposure apparatus, including carrying out the imaging of the mask onto the detector unit using a plurality of individual illumination settings set in the illumination optical unit to produce a plurality of individual imagings that differ from one another with regard to the illumination setting set in the illumination optical unit;
wherein the individual illumination settings each has a constantly linear polarization distribution, and a sum of the individual illumination settings in terms of light distribution and polarization corresponds to the predefined illumination setting that has the quasi-tangential polarization distribution.

2. The method according to claim 1 , wherein the illumination setting to be set in the microlithographic projection exposure apparatus is a quadrupole illumination setting or an annular illumination setting.

3. The method according to claim 1 , wherein the plurality of individual imagings are carried out without modification of the imaging optical unit.

4. The method according to claim 1 , wherein different illumination settings for the individual imagings are set by regions of a polarization-influencing optical element arranged in the illumination optical unit, from which regions light passes to the mask during the respective individual imaging, being chosen to be different from one another for the individual imagings.

5. The method according to claim 1 , wherein different illumination settings for the individual imagings are set by exchanging or displacing at least one stop in the illumination optical unit.

6. The method according to claim 1 , wherein different illumination settings for the individual imagings are set using a mirror arrangement comprising a multiplicity of mirror elements that can be set independently of one another.

7. The method according to claim 1 , wherein during the evaluation of the image data recorded by the detector unit during the individual imagings, a conversion of said image data is carried out in each case, during which conversion said image data are subjected to a polarization-dependent weighting.

8. The method according to claim 7 , wherein the image data recorded by the detector unit during the individual imagings, following said conversion, are added, added in weighted fashion, averaged or averaged in weighted fashion.

9. A method for characterizing a mask for microlithography, wherein structures of a mask intended for use in a lithography process in a microlithographic projection exposure apparatus are illuminated by an illumination optical unit and wherein the mask is imaged onto at least one detector unit by an imaging optical unit, wherein image data recorded by the detector unit are evaluated in an evaluation unit,
wherein for emulating an illumination setting predefined for the lithography process in the microlithographic projection exposure apparatus, the imaging of the mask onto the at least one detector unit is carried out using a plurality of individual illumination settings set in the illumination optical unit or a plurality of individual polarization-influencing effects of the imaging optical unit to produce a plurality of individual imagings that differ from one another with regard to the illumination setting set in the illumination optical unit or the polarization-influencing effect of the imaging optical unit;
wherein the illumination setting to be set in the microlithographic projection exposure apparatus has a quasi-tangential polarization distribution;
wherein the individual illumination settings or polarization-influencing effects each has a constantly linear polarization distribution, and a sum of the individual illumination settings or the individual polarization-influencing effects in terms of light distribution and polarization corresponds to the illumination setting to be set in the microlithographic projection exposure apparatus that has the quasi-tangential polarization distribution;
wherein during the evaluation of the image data recorded by the at least one detector unit during the individual imagings, a conversion of said image data is carried out in each case, during which conversion said image data are subjected to a polarization-dependent weighting; and
wherein the image data recorded by the at least one detector unit during the individual imagings, following said conversion, are added, added in weighted fashion, averaged or averaged in weighted fashion.

10. The method according to claim 9 , wherein at least two mutually different detector units or at least two different regions of a detector unit are used for recording the image data during the individual imagings.

11. The method according to claim 10 , wherein light portions of different polarization properties are recorded simultaneously by at least two mutually different detector units or by at least two different regions of a detector unit.

12. An apparatus for characterizing a mask for microlithography, comprising:
an illumination optical unit for illuminating structures on the mask,
a detector unit,
an imaging optical unit for imaging the mask onto the detector unit, and
an evaluation unit for evaluating the image data recorded by the detector unit, wherein the apparatus is configured to carry out a method for characterizing a mask for microlithography, wherein structures of a mask intended for use in a lithography process in a microlithographic projection exposure apparatus are illuminated by the illumination optical unit and wherein the mask is imaged onto the detector unit by the imaging optical unit, wherein image data recorded by the detector unit are evaluated in the evaluation unit,
wherein for emulating an illumination setting predefined for the lithography process in the microlithographic projection exposure apparatus, the imaging of the mask onto the detector unit is carried out using a plurality of individual illumination settings set in the illumination optical unit to produce a plurality of individual imagings that differ from one another with regard to the illumination setting set in the illumination optical unit,
wherein the illumination setting predefined for the lithography process in the microlithographic projection exposure apparatus has a quasi-tangential polarization distribution, and
wherein the individual illumination settings each has a constantly linear polarization distribution, and a sum of the individual illumination settings in terms of light distribution and polarization corresponds to the illumination setting predefined for the lithography process in the microlithographic projection exposure apparatus that has the quasi-tangential polarization distribution.

13. The apparatus of claim 12 in which the apparatus is configured to characterize a mask for microlithography in which structures of the mask are intended for use in a lithography process in a microlithographic projection exposure apparatus having a quadrupole illumination setting or an annular illumination setting.

14. The apparatus of claim 12 in which the plurality of individual imagings are carried out without modification of the imaging o

Assignees

• Zeiss Carl Smt Gmbh

Inventors

• Seitz Holger
• Buttgereit Ute
• Thaler Thomas
• Frank Thomas
• Matejka Ulrich
• Deguenther Markus
• Birkner Robert
• Grau Dominik

Classifications

• G03F7/706851

  Detection branch, e.g. detector arrangements, polarisation control, wavelength control or dark/bright field detection · CPC title

• G03F7/706849

  Irradiation branch, e.g. optical system details, illumination mode or polarisation control · CPC title

• G03F7/70566

  Polarisation control · CPC title

• G03F7/70508

  Data handling in all parts of the microlithographic apparatus, e.g. handling pattern data for addressable masks or data transfer to or from different components within the exposure apparatus · CPC title

• G03F7/70141

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