Granted Patent B1

US 8,182,609 · App. 12/188,564 · Granted May 22, 2012

Abstract

Claims (30)

1. A method for cleaning a surface of a substrate, comprising:

directing a laser through a pellicle towards at least one radiation-produced inorganic particle disposed on a substrate, the particle having an absorption spectrum with at least one local maximum at about 7 μm, the laser having a wavelength that is substantially the same as the local maximum of the particle absorption spectrum;

generating a thermal increase in the particle;

directing an airflow onto the pellicle to reduce thermal build up in the pellicle; and

removing the particle from the substrate by thermal decomposition.

2. The method of claim 1 , wherein the substrate includes at least one thin film layer.

3. The method of claim 2 , wherein the thin film layer is patterned and includes void areas under which respective portions of the substrate are exposed.

4. The method of claim 1 , further comprising maintaining a temperature of the substrate below a threshold temperature to prevent damage thereto.

5. The method of claim 1 , wherein the substrate has an absorption spectrum that does not include a local maximum at about 7 μm.

6. The method of claim 1 , wherein the particle has an absorption spectrum with a local maximum at about 3 μm.

7. A method for increasing the useable lifetime of a photomask substrate, comprising:

directing electromagnetic radiation through a pellicle towards a radiation-produced contamination on a photomask substrate, the contamination having an absorption spectrum with at least one local maximum at about 7 μm, the electromagnetic radiation having a wavelength that is substantially the same as the local maximum of the contamination absorption spectrum;

generating a thermal increase in the contamination;

directing an airflow onto the pellicle to reduce thermal build up in the pellicle; and

removing at least a portion of the contamination by thermal decomposition.

8. The method of claim 7 , wherein the photomask substrate is at least partially enclosed within the pellicle.

9. The method of claim 7 , wherein the photomask substrate includes at least one thin film layer.

10. The method of claim 7 , wherein the thin film layer is patterned and includes voids under which respective portions of the photomask substrate are exposed.

11. The method of claim 7 , further comprising maintaining a temperature of the photomask substrate below a threshold temperature to prevent damage thereto.

12. The method of claim 7 , wherein the particle is inorganic.

13. The method of claim 7 , wherein the substrate has an absorption spectrum that does not include a local maximum at about 7 μm.

14. A method for cleaning a surface of a substrate at least partially enclosed within a pellicle, comprising:

directing a laser through a pellicle film towards a radiation-produced contaminating layer on a substrate, the contaminating layer having an absorption spectrum with at least one local maximum at about 7 μm, the laser having a wavelength that is substantially the same as the local maximum of the contaminating layer absorption spectrum;

generating a thermal increase in the contaminating layer;

directing an airflow onto the pellicle film to reduce thermal build up in the pellicle; and

removing at least a portion of the contaminating layer from the substrate by thermal decomposition.

15. The method of claim 14 , wherein the contaminating layer is a haze layer.

16. The method of claim 15 , wherein the haze layer is an ammonium sulfate haze layer.

17. The method of claim 14 , wherein the contaminating layer is inorganic.

18. The method of claim 14 , wherein the substrate has an absorption spectrum that does not include a local maximum at about 7 μm.

Assignments (6)