METHOD AND DEVICE FOR MONITORING MULTIPLE MIRROR ARRAYS IN AN ILLUMINATION SYSTEM OF A MICROLITHOGRAPHIC PROJECTION EXPOSURE APPARATUS

• US 20100039629A1
• Filed: 07/21/2009
• Published: 02/18/2010
• Est. Priority Date: 02/06/2007
• Status: Active Grant

• Current Assignee: CARL Zeiss SMT GmbH (Carl-Zeiss-Stiftung)
• Original Assignee: Carl Zeiss AG (Carl-Zeiss-Stiftung)
• Inventors: Deguenther, Markus, Maul, Manfred, Kwan, Yim-Bun Patrick, Major, Andras G., Layh, Michael, Wangler, Johannes, Fiolka, Damian, Bach, Florian, Horn, Jan, Patra, Michael, Xalter, Stefan, Eisenmenger, Johannes
• Granted Patent: US 8,339,577 B2
• Time in Patent Office: Days
• US Class Current: 355/67
• CPC Class Codes: G01B 11/002 for measuring two or more coordinates
• CPC Class Codes: G01B 11/272 using photoelectric detection means
• CPC Class Codes: G01M 11/30 Testing of optical devices, constituted by fibre optics or optical waveguides
• CPC Class Codes: G01N 21/55 Specular reflectivity
• CPC Class Codes: G02B 26/0833 the reflecting element being a micromechanical device, e.g. a MEMS mirror, DMD G02B26/0825 takes precedence; micromechanical devices in general B81B
• CPC Class Codes: G03F 7/70058 Mask illumination systems
• CPC Class Codes: G03F 7/70116 Off-axis setting using a programmable means, e.g. liquid crystal display [LCD], digital micromirror device [DMD] or pupil facets
• CPC Class Codes: G03F 7/70133 Measurement of illumination distribution, in pupil plane or field plane
• CPC Class Codes: G03F 7/702 Reflective illumination, i.e. reflective optical elements other than folding mirrors, e.g. extreme ultraviolet [EUV] illumination systems
• CPC Class Codes: G03F 7/70258 Projection system adjustments, e.g. adjustments during exposure or alignment during assembly of projection system
• CPC Class Codes: G03F 7/70291 Addressable masks, e.g. spatial light modulators [SLMs], digital micro-mirror devices [DMDs] or liquid crystal display [LCD] patterning devices
• CPC Class Codes: G03F 7/70516 Calibration of components of the microlithographic apparatus, e.g. light sources, addressable masks or detectors
• CPC Class Codes: G03F 7/7085 Detection arrangement, e.g. detectors of apparatus alignment possibly mounted on wafers, exposure dose, photo-cleaning flux, stray light, thermal load
• CPC Class Codes: G05B 13/048 using a predictor
• CPC Class Codes: Y10S 359/904 Micromirror

Abstract

An illumination system of a microlithographic projection exposure apparatus has a pupil surface and an essentially flat arrangement of desirably individually drivable beam deviating elements for variable illumination of the pupil surface. Each beam deviating element allows deviation of a projection light beam incident on it to be achieved as a function of a control signal applied to the beam deviating element. A measurement illumination instrument directs a measurement light beam, independent of the projection light beams, onto a beam deviating element. A detector instrument records the measurement light beam after deviation by the beam deviating element. An evaluation unit determines the deviation of the projection light beam from measurement signals provided by the detector instrument.

Claims

1. An illumination system having a pupil surface, the illumination system comprising:

an essentially flat arrangement of beam deviating elements configured to variably illuminate the pupil surface of the illumination system, each beam deviating element configured to allow deviation of a projection light beam incident thereon in response to a control signal applied to the beam deviating element; and

a measurement illumination instrument configured to direct a measurement light beam independent of the projection light beams onto a beam deviating element;

a detector instrument configured to record the measurement light beam after deviation by the beam deviating element; and

an evaluation unit to determine the deviation of the projection light beam from measurement signals provided by the detector instrument,

wherein the illumination system is configured to be used in a microlithographic projection exposure apparatus.

2. The illumination system according to claim 1, wherein the beam deviating elements are individually drivable.

3. The Illumination system according to claim 1, wherein the measurement light beam can be directed onto the beam deviating element with an incidence direction which differs from the incidence direction with which a projection light beam assigned to the beam deviating element strikes the beam deviating element.

4. The illumination system according to claim 1, wherein the measurement light beam can be directed onto the beam deviating element with an incidence direction which such that measurement light beam cannot strike the pupil surface independently of the beam deviation caused by the beam deviating element.

5. The illumination system according to claim 1, wherein the beam deviating elements comprise tiltable mirrors, and each tiltable mirror has a reflecting mirror surface.

6. The illumination system according to claim 5, wherein a plurality of measurement light beams can be directed onto an individual reflecting mirror surface, and a curvature of a reflecting mirror surface can be ascertained by the evaluation unit on the basis of the different deviations which are experienced by the measurement light beams on the reflecting mirror surface.

7. The illumination system according to claim 5, wherein a cross section of the measurement light beam can be recorded by the detector instrument, and a curvature of a reflecting mirror surface can be ascertained by the evaluation unit on the basis of the ascertained cross section.

8. The illumination system according to claim 1, further comprising a housing in which the beam deviating elements are arranged, wherein the housing has a window which is transparent for both the measurement light beam and the projection light beam.

9. The illumination system according to claim 8, wherein p-polarised measurement light beams can be directed at the Brewster angle onto the window by the measurement illumination instrument.

10. The illumination system according to claim 8, wherein the transparent window has an antireflection coating designed for the incident projection light, and the wavelength of the measurement light beam is greater than the thickness of the antireflection coating.

11. The illumination system according to claim 1, further comprising an incidence-side optical system between the measurement illumination instrument and the beam deviating element along a path of the measurement light from the beam deviating element and measurement illumination instrument.

12. The illumination system according to claim 11, wherein the incidence-side optical system comprises at least one collimator to generate parallel ray bundles.

13. The illumination system according to claim 1, further comprising an emergence-side optical system between the beam deviating element and the detector instrument along a path of the measurement light from beam deviating element and the detector instrument.

14. The illumination system according to claim 1, wherein the detector instrument comprises at least one image recorder configured as a 4-quadrant detector.

15. The illumination system according to claim 1, wherein the measurement illumination instrument can generate a luminous pattern from which the measurement light beams emerge, and the detector instrument comprises a camera configured to record detail of the pattern after deviation by the beam deviation element.

16. An apparatus, comprising:

an illumination system according to claim 1; and

a projection objective,

wherein the apparatus is a microlithographic projection exposure apparatus.

17. A method, comprising:

directing a measurement light beam independent of projection light beams onto a beam deviating element of an illumination system configured to be used in a microlithographic projection exposure apparatus,

recording the measurement light beam after deviation by the beam deviating element; and

determining therefrom the deviation of the projection light beam assigned to the beam deviating element to determine the deviation of projection light beams in the illumination system.

18. The method of claim 17, wherein the illumination system comprises an essentially flat arrangement of beam deviating elements configured to variably illuminate a pupil surface of the illumination system.

19. The method of claim 18, wherein each beam deviating element is configured to allow deviation of a projection light beam incident thereon based on a control signal applied to the beam deviating element.

20. The method of claim 18, wherein the beam deviating elements are individually drivable.