Lithographic apparatus and method

Abstract

A lithographic apparatus is provided with a measurement apparatus constructed and arranged to use surface plasmon resonance to detect contamination of a surface within the lithographic apparatus.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the invention will now be described, by way of example only, with reference to the accompanying schematic drawings in which corresponding reference symbols indicate corresponding parts, and in which:

FIG. 1 schematically depicts a lithographic apparatus that includes a contamination detection system according to an embodiment of the present invention;

FIG. 2 schematically depicts the contamination detection system shown in FIG. 1 in more detail;

FIG. 3 depicts an operating principle of the contamination detection system of FIG. 2;

FIG. 4 schematically depicts another embodiment of the contamination detection system;

FIG. 5 schematically depicts another embodiment of the contamination detection system;

FIG. 6 schematically depicts another embodiment of the contamination detection system;

FIG. 7 a schematically depicts another embodiment of the contamination detection system;

FIG. 7 b schematically depicts an embodiment of a prism of the contamination detection system of FIG. 7a; and

FIG. 8 depicts an operating principle of the contamination detection system of FIG. 7a.

Claims

1. A lithographic apparatus provided with a measurement apparatus constructed and arranged to use surface plasmon resonance to detect contamination of a surface within the lithographic apparatus.

2. The lithographic apparatus of claim 1, wherein the measurement apparatus is a surface plasmon resonance spectrometer.

3. The lithographic apparatus of claim 1, wherein the measurement apparatus is a surface enhanced Raman spectrometer.

4. The lithographic apparatus of claim 1, wherein the measurement apparatus is a surface enhanced resonance Raman spectrometer.

5. The lithographic apparatus of claim 1, wherein the surface is a measurement surface and is positioned such that the measured contamination of the measurement surface allows the contamination of an optical surface of the lithographic apparatus to be inferred.

6. The lithographic apparatus of claim 5, wherein the measurement surface is provided on or adjacent to a prism, or is provided with a grating structure.

7. The lithographic apparatus of claim 5, wherein a waveguide is provided at the measurement surface.

8. The lithographic apparatus of claim 2, wherein the measurement apparatus comprises a detector constructed and arranged to detect contamination on a measurement surface such that contamination of an optical surface of the lithographic apparatus may be inferred therefrom, the measurement surface being one of a plurality of layers provided on a substrate, the plurality of layers including at least two metal layers and being capable of supporting a waveguide mode.

9. The lithographic apparatus of claim 8, wherein the measurement apparatus further comprises a polarization controller arranged to control the polarization of a radiation beam incident upon the measurement surface, and the plurality of layers are arranged such that s-polarized radiation couples to the waveguide mode and p-polarized radiation excites plasmons which have a resonance that is influenced by contamination on the measurement surface.

10. The lithographic apparatus of claim 9, wherein the polarization controller is a photo-electric modulator which is arranged to modulate the polarization and the detector is connected to a discrimination apparatus which discriminates between the modulated polarizations.

11. The lithographic apparatus of claim 4, wherein the measurement apparatus comprises radiation sources arranged to emit radiation at first and second wavelengths, the difference between the wavelengths being selected to correspond to a peak of a Raman spectrum of the contamination, and a detector arranged to detect Raman scattered radiation.

12. The lithographic apparatus of claim 1, wherein the apparatus includes a radiation source which may be one of a broadband source, a single wavelength source or a tuneable source.

13. The lithographic apparatus of claim 12, wherein the radiation source includes a Fourier transform spectrometer.

14. The lithographic apparatus of claim 5, wherein the measurement surface forms part of the optical surface.

15. A method of detecting contamination within a lithographic apparatus, the method comprising: measuring contamination of a surface within the lithographic apparatus using surface plasmon resonance.

16. The method of claim 15, wherein said measuring comprises monitoring a radiation wavelength and/or angle that resonantly excites surface plasmons, and wherein a shift in the wavelength and/or angle is indicative of contamination on the surface.

17. The method of claim 15, wherein said measuring comprises monitoring a spectrum of Raman scattered radiation from the surface to determine the presence and/or nature of contamination on the surface.

18. The method of claim 17, wherein the amount of Raman scattered radiation is enhanced by exciting transitions in the contamination, the transitions being excited by directing radiation at first and second wavelengths at the measurement surface, the difference between the wavelengths being selected to correspond to a peak of a Raman spectrum of the contamination.

19. The method of claim 15, wherein the surface being measured forms part of an optical surface.

20. The method of claim 19, wherein the surface being measured is provided on or adjacent to a prism, or is provided with a grating structure.

21. A lithographic apparatus provided with a measurement apparatus constructed and arranged to use tunneling of photons through a metal layer to detect contamination of a surface within the lithographic apparatus.

22. The lithographic apparatus of claim 21, wherein the measurement apparatus is arranged to measure coupling of incident radiation into a guided mode.

23. The lithographic apparatus of claim 22, wherein the measurement apparatus is arranged such that the guided mode is on an opposite side of the metal layer from the location at which the incident radiation is incident on the metal layer.

24. The lithographic apparatus of claim 22, wherein the guided mode is centered on a waveguide, and wherein the waveguide is arranged such that during propagation of radiation along the waveguide, some of the radiation overlaps with the contaminated surface.

25. A method of detecting contamination on a contaminated surface within a lithographic apparatus, the method comprising: directing incident radiation at a metal layer; anddetecting coupling of the incident radiation into a guided mode through the metal layer.

26. The method of claim 25, wherein the guided mode is centered on a waveguide, and wherein the waveguide is arranged such that during propagation of radiation along the waveguide, some of the radiation overlaps with the contaminated surface.

27. A lithographic apparatus comprising: a pattern device constructed and arranged to pattern radiation;a projection system constructed and arranged to project the patterned radiation onto a substrate; anda contamination detection system constructed and arranged to detect contamination of a surface within the lithographic apparatus using surface plasmon resonance.

28. The lithographic apparatus of claim 27, wherein the contamination detection system comprises a surface plasmon resonance spectrometer.

29. The lithographic apparatus of claim 27, wherein the contamination detection system comprises a surface enhanced Raman spectrometer.

30. The lithographic apparatus of claim 27, wherein the contamination detection system comprises a surface enhanced resonance Raman spectrometer.

31. A method for manufacturing a device with a lithographic apparatus, the method comprising: patterning radiation with a patterning device;projecting the patterned radiation onto a substrate with a projection system; anddetecting contamination of a surface within the lithographic apparatus using surface plasmon resonance.