Catadioptric projection objective including a reflective optical component and a measuring device

Patent metadata

Field	Value
Publication number	US-10146137-B2
Application number	US-201213423344-A
Country	US
Kind code	B2
Filing date	Mar 19, 2012
Priority date	Oct 28, 2009
Publication date	Dec 4, 2018
Grant date	Dec 4, 2018

Abstract

A catadioptric projection objective for images an object field onto an image field via imaging radiation. The projection objective includes at least one reflective optical component and a measuring device. The reflective optical component, during the operation of the projection objective, reflects a first part of the imaging radiation and transmits a second part of the imaging radiation. The reflected, first part of the imaging radiation at least partly contributes to the imaging of the object field. The transmitted, second part of the imaging radiation is at least partly fed to a measuring device. This allows a simultaneous exposure of the photosensitive layer at the location of the image field with the imaging radiation and monitoring of the imaging radiation with the aid of the measuring device.

First claim

What is claimed is:

1. A projection objective configured to image an object field onto an image field via imaging radiation, the projection objective comprising:
a reflective optical component; and
a measuring device,
wherein the projection objective is a catadioptric projection objective, and
wherein during use of the projection objective:
a region of the reflective optical component is illuminated with the imaging radiation;
the region of the reflective optical component includes a first partial region that is illuminated with the imaging radiation and a second partial region that is illuminated with the imaging radiation;
the second partial region of the reflective optical component is outside the first partial region of the reflective optical component;
the first partial region has a first transmittance for the imaging radiation;
the second partial region has a second transmittance for the imaging radiation;
the first transmittance is greater than the second transmittance;
the reflective optical component reflects a first part of the imaging radiation;
the region of the reflective optical component transmits a second part of the imaging radiation;
the reflected, first part of the imaging radiation at least partly contributes to imaging of the object field into the image field;
the transmitted, second part of the imaging radiation is at least partly fed to the measuring device without first impinging on the image field;
the transmitted, second part of the imaging radiation is less than 10% of the imaging radiation impinging on the reflective optical component.

2. The projection objective of claim 1 , wherein the reflective optical component is arranged near a pupil of the projection objective.

3. The projection objective of claim 1 , wherein the reflective optical component is arranged near a field of the projection objective.

4. The projection objective of claim 1 , wherein the reflective optical component has a curvature.

5. The projection objective of claim 1 , wherein the transmitted, second part of the imaging radiation is between 0.1% and 5% of the imaging radiation which impinges on the region of the reflective optical component.

6. The projection objective of claim 1 , wherein the measuring device comprises a component configured to provide a spatially resolved measurement of an intensity of the transmitted, second part of the imaging radiation.

7. The projection objective of claim 1 , wherein, during use of the projection objective, each point of the region of the reflective optical component transmits a part of the imaging radiation which is fed to the measuring device.

8. The projection objective of claim 7 , wherein the region of the reflective optical component comprises a plurality of first partial regions which are arranged in the form of a regular grid.

9. The projection objective of claim 1 , wherein during the operation of the projection objective, the imaging radiation transmitted by the second partial region is less than 0.5% of the imaging radiation which impinges on the reflective optical component.

10. The projection objective of claim 9 , wherein the region of the reflective optical component comprises a plurality of first partial regions which are arranged in the form of a regular grid.

11. The projection objective of claim 1 , wherein the measuring device comprises a measuring optical unit which, during use of the projection objective, directs the transmitted, second part of the imaging radiation onto a radiation-sensitive sensor.

12. The projection objective of claim 1 , wherein the reflective optical component comprises a reflective coating, and the measuring device comprises a radiation-sensitive sensor which is directly connected to the reflective optical component so that, during use of the projection objective, the transmitted, second part of the imaging radiation impinges on the radiation-sensitive sensor without passing through further optical components between the reflective coating and the radiation-sensitive sensor.

13. The projection objective of claim 1 , wherein the measuring device comprises a component which, during use of the projection objective, emits secondary radiation upon passage or absorption of the transmitted, second part of the imaging radiation, and wherein the secondary radiation has a different wavelength from the imaging radiation.

14. The projection objective of claim 1 , further comprising a correction mechanism configured to correct an imaging quality of the projection objective.

15. The projection objective of claim 14 , further comprising an evaluation unit, wherein, during use of the projection objective, the measuring device generates a measurement signal that is forwarded to the evaluation unit, and the evaluation unit, with the aid of the measurement signal, provides a control signal to drive the correction mechanism.

16. The projection objective of claim 1 , wherein the imaging radiation has a wavelength of 193 nm.

17. An apparatus, comprising:
an illumination system; and
the projection objective of claim 1 ,
wherein the apparatus is a microlithography projection exposure apparatus.

18. The projection objective of claim 1 , wherein an intensity of the imaging light transmitted by the first partial region is greater than an intensity of the imaging light transmitted by the second partial region.

19. The projection objective of claim 1 , wherein:
the region of the reflective optical element comprises a plurality of first regions that transmit imaging radiation during use of the projection objective;
for each of the first regions, a transmittance for the imaging radiation is greater than the second transmittance; and
during use of the projection objective, a sum of the imaging radiation transmitted by the second regions is less than 0.5% of the imaging radiation which impinges on the reflective optical component.

20. A projection objective configured to image an object field onto an image field via imaging radiation, the projection objective comprising:
a reflective optical component; and
a measuring device,
wherein the projection objective is a catadioptric projection objective, and
wherein during use of the projection objective:
a region of the reflective optical component is illuminated with the imaging radiation;
the region of the reflective optical component includes a first partial region that is illuminated with the imaging radiation and a second partial region that is illuminated with the imaging radiation;
the second partial region of the reflective optical component is outside the first partial region of the reflective optical component;
the reflective optical component reflects a first part of the imaging radiation;
the region of the reflective optical component transmits a second part of the imaging radiation;
an intensity of the imaging light transmitted by the first partial region is greater than an intensity of the imaging light transmitted by the second partial region;
the reflected, first part of the imaging radiation at least partly contributes to imaging of the object field into the image field;
the transmitted, second part of the imaging radiation is at least partly fed to the measuring device without first impinging on the image field;
the transmitted, second part of the imaging radiation is less than 10% of the imaging radiation impinging on the reflective optical component.

Assignees

• Bleidistel Sascha
• Gruner Toralf
• Zaczek Christoph
• Mueller Ralf
• Zeiss Carl Smt Gmbh

Inventors

• Bleidistel Sascha
• Gruner Toralf
• Zaczek Christoph
• Mueller Ralf

Classifications

• G02B17/0856

  comprising a refractive element with a reflective surface, the reflection taking place inside the element, e.g. Mangin mirrors · CPC title

• G03F7/706

  Aberration measurement · CPC title

• G03F7/70225

  Optical aspects of catadioptric systems, i.e. comprising reflective and refractive elements · CPC title

• G02B13/143

  for use with ultraviolet radiation · CPC title

• G02B17/0892

  specially adapted for the UV · CPC title