Method and apparatus for measuring thickness and optical properties of a thin-film on a substrate

1. A metrology method comprising:

emitting an incident light beam onto a production substrate including an anti-reflective layer;

receiving a reflected light beam;

determining a spectrum of the reflected light beam;

selecting a suppression band based on an expected wavelength representative of a portion of the anti-reflective layer; and

determining a property of the anti-reflective layer based on a portion of the spectrum in the selected suppression band.

2. The method of claim 1 , wherein the suppression band selection is further based on a suppression, by the anti-reflective layer, of at least some of the reflected light beam from a lower layer within the production substrate below the anti-reflective layer.

3. The method of claim 1 , wherein determining the property of the anti-reflective layer comprises determining an effective wavelength within the reflected light beam and determining the property of the anti-reflective layer based on the effective wavelength.

4. The method of claim 1 , wherein the property of the anti-reflective layer is a thickness, a reflectivity, a refractive index, or an extinction coefficient.

5. The method of claim 1 , further comprising:

applying a photosensitive emulsion over the anti-reflective layer after determining the property of the anti-reflective layer; and

adjusting an exposure time for the photosensitive emulsion based on the property determination of the anti-reflective layer.

6. The method of claim 1 , further comprising:

determining a desired adjustment to a process tool based on the property determination of the anti-reflective layer; and

providing an instruction to the process tool to make the desired adjustment.

7. The method of claim 1 , further comprising:

selecting a transmission band outside the suppression band; and

determining a property of a lower layer below the anti-reflective layer based on the spectrum of the transmission band.

8. The method of claim 7 , wherein the property of the lower layer below the anti-reflective layer is a thickness, a reflectivity, a refractive index, or an extinction coefficient.

9. The method of claim 1 , wherein emitting the incident light beam onto a production substrate comprises emitting an incident light beam while moving the production substrate.

10. The method of claim 1 , wherein the production substrate is a wafer.

11. The method of claim 1 , wherein the production substrate is a lithographic mask.

12. The method of claim 1 , wherein a suppression band is less than about 350 nanometers.

13. The method of claim 1 , wherein emitting the incident light beam onto a production substrate comprises emitting the incident light beam for less than two hundred milliseconds.

14. A metrology tool comprising:

an emitter configured to emit an incident light beam at a production substrate including an anti-reflective layer;

a receiver configured to receive a reflected light beam from the production substrate;

a spectrometer configured to determine a digital signal representing an intensity of a wavelength within the reflected light beam; and

a processor configured to:

determine a spectrum of the reflected light beam from the digital signal;

select a suppression band based on an expected wavelength representative of a portion of the anti-reflective layer; and

determine a property of the anti-reflective layer based on a portion of the spectrum in the selected suppression band.

15. The metrology tool of claim 14 , wherein a diameter of the incident light beam is greater than 10 millimeters.

16. The metrology tool of claim 14 , the production substrate comprises a plurality of features in a lower layer below the anti-reflective layer.

17. The metrology tool of claim 14 , wherein a suppression band of the anti-reflective layer is less than about 350 nanometers.

18. The metrology tool of claim 14 , wherein the emitter is further configured to emit the incident light beam for less than one second.

19. The metrology tool of claim 14 , further comprising a mount configured to attach the emitter and the receiver to a process tool.

20. The metrology tool of claim 14 , further comprising a mount configured to position the emitter over a substrate path of a process tool.

21. The metrology tool of claim 14 , further comprising a support configured to position the emitter and the receiver over a substrate transport between a first process tool and a second process tool.

22. A metrology method comprising:

emitting multiple wavelength radiation beam onto an area of a production substrate including an anti-reflective layer;

detecting intensities and wavelengths of a reflected radiation beam;

analyzing the intensities and wavelengths to determine a spectrum of the intensities at respective wavelengths;

transforming the spectrum of the intensities into a frequency spectrum;

selecting a suppression band based on an expected wavelength representative of a portion of the anti-reflective layer; and

determining a property of the anti-reflective layer based on a portion of the spectrum in the selected suppression band.

23. The method of claim 22 , wherein the area comprises at least a portion of two or more die.

24. The method of claim 22 , wherein the anti-reflective layer is over a die comprising one or more features within one or more lower layers.