Tunable wavelength illumination system

1. A wafer alignment system for aligning a wafer having a plurality of alignment targets which diffract radiation, comprising:

a radiation source configured to convert narrow-band radiation into continuous, flat, and, broad-band radiation;

an acoustically tunable narrow pass-band filter configured to:

filter the broad-band radiation into narrow-band linearly polarized radiation, wherein the narrow-band linearly polarized radiation is focused on the plurality of alignment targets to enable alignment of the wafer, and

select a plurality of narrow-band wavelength set points at a same time or nearly the same time; and

a relay, and mechanical interface configured to:

receive the narrow-band linearly polarized radiation from the acoustically tunable narrow pass-band filter; and

adjust a profile, of the received narrow-band linearly polarized radiation based on physical properties of the alignment targets.

2. The system of claim 1 , wherein the filter is configured to modulate intensity and wavelength of the broad-band radiation produced by the radiation source.

3. The system of claim 1 , wherein the filter is configured to provide a plurality of pass-band filters at a same time or nearly the same time.

4. The system of claim 1 , wherein the radiation source comprises a fiber amplifier configured to generate high intensity short pulse radiation with a high repetition rate.

5. The system of claim 1 , wherein the filter is an Acousto-Optical Tunable Filter (AOTF).

6. The system of claim 1 , wherein the filter comprises a volume medium configured to cause Bragg diffraction.

7. The system of claim 1 , wherein the narrow-band radiation has a mean wavelength of approximately 980 nm.

8. The system of claim 1 , wherein the broad-band radiation ranges from 450 nm to 2500 nm.

9. A method to align a wafer in a lithographic apparatus, comprising:

generating a first high intensity short-pulse radiation;

propagating the first radiation through a non-linear device to generate a second continuous, broad, and flat spectrum radiation;

filtering, using an acoustically tunable filter, the second radiation acoustically to generate narrow-band linearly polarized radiation;

selecting a plurality of narrow-band wavelength set points at a same time or nearly the same time;

receiving, using a relay and mechanical interface, the narrow-band linearly polarized radiation from the acoustically tunable filter;

adjusting a profile of the received narrow-band linearly polarized radiation; and

illuminating an alignment target with the narrow-band radiation to enable alignment of the wafer.

10. The method of claim 9 , wherein the filtering comprises modulating intensity and wavelength of the second radiation.

11. The method of claim 9 , wherein the filtering comprises using a plurality of pass-band filters at a same time or nearly the same time.

12. The method of claim 9 , wherein the first radiation is a high intensity short pulse radiation with a high repetition rate.

13. An illumination system in a lithographic apparatus, comprising:

a radiation source configured to convert narrow-band radiation into continuous, flat, and broad-band radiation;

an acoustically tunable narrow pass-band filter configured to:

filter the broad-band radiation into narrow-band linearly polarized radiation, wherein the narrow-band linearly polarized radiation is focused on alignment targets of a wafer to enable alignment of the wafer, and

select a plurality of narrow-band wavelength set points at a same time or nearly the same time; and

a relay and mechanical interface configured to:

receive the narrow-band linearly polarized radiation from the acoustically tunable narrow pass-band filter; and

adjust a profile of the received narrow-band linearly polarized radiation based on physical properties of the alignment targets.

14. The system of claim 13 , wherein the filter is configured to modulate intensity and wavelength of the broad-band radiation produced by the radiation source.

15. The system of claim 13 , wherein the filter is configured to provide a plurality of pass-band filters at a same time or nearly the same time.

16. The system of claim 13 , wherein the radiation source comprises a fiber amplifier configured to generate high intensity short pulse radiation with a high repetition rate.

17. The system of claim 13 , wherein the radiation source has a repetition rate of 80 Mhz.

18. An alignment system comprising:

an illumination source configured to provide tunable narrow-band wavelengths over a continuous broad spectral range, wherein the illumination source comprises:

an acoustically tunable filter configured to:

filter a broad-band radiation into narrow-band linearly polarized radiation, wherein the narrow band linearly polarized radiation is focused on alignment marks of a wafer to enable alignment of the wafer, and

select a plurality of narrow-band wavelength set points at a same time or nearly the same time for detecting a position of the alignment mark on the wafer to align the wafer using the alignment mark;

a relay and mechanical interface confirmed to:

receive the narrow-band linearly polarized radiation from the acoustically tunable filter; and

adjust a profile of the received narrow-band linearly polarized radiation based on physical properties of the alignment targets; and

an optics system configured to cover the continuous broad spectral range of the illumination source.

19. The alignment system of claim 18 , wherein the tunable filter is configured to enable selection of wavelengths in a spectral tuning range of about 450 nm to 2500 nm.

20. The alignment system of claim 18 , wherein the tunable filter comprises a library of spectral filters.

21. The system of claim 18 , wherein each of the plurality of narrow-band wavelength set points is a few or several nanometers wide.