Transport system for an extreme ultraviolet light source

Patent metadata

Field	Value
Publication number	US-9560730-B2
Application number	US-201314022026-A
Country	US
Kind code	B2
Filing date	Sep 9, 2013
Priority date	Sep 9, 2013
Publication date	Jan 31, 2017
Grant date	Jan 31, 2017

Abstract

Free radicals that combine with debris that is created by converting a target mixture to plasma that emits EUV light are received at a first opening defined by a first end of a conduit, the conduit including a material that passes the free radicals and the conduit including a sidewall that extends away from the first opening and defines at least one other opening, the at least one other positioned to release the free radicals toward an element that accumulates the debris on a surface. The free radicals in the conduit are directed toward the at least one other opening. The free radicals are passed through the at least one other opening and to the surface of the element to remove the debris from the surface of the element without removing the element from the EUV light source.

First claim

What is claimed is:

1. A method of cleaning an element in an extreme ultraviolet (EUV) light source, the method comprising:
arranging a conduit relative to the element, the element being inside of a vacuum chamber of the EUV light source and in the path of EUV light emitted from a plasma and debris created by converting a target material to the plasma that emits the EUV light, the conduit comprising a sidewall that comprises a curved portion and a linear portion, the conduit being arranged with the linear portion passing through a wall of the vacuum chamber and the curved portion inside the vacuum chamber;
receiving, at a first opening defined by a first end of the conduit, a moving gas and free radicals, the moving gas configured to carry the free radicals in the conduit, and the free radicals being configured to combine with the debris that is created by converting the target material to plasma that emits EUV light, the conduit comprising a metallic material, an inner surface of the conduit being coated with a material having a recombination coefficient of 5×10 −3 or less, and the conduit defining a plurality of other openings, the other openings passing through the curved portion of the sidewall and positioned to release the free radicals toward an element that accumulates the debris on a surface;
directing the moving gas to carry the free radicals in the conduit toward the plurality of other openings, the moving gas having a velocity and generating a back pressure in the conduit, the back pressure and the velocity being in different directions;
reducing an amount of time that the free radicals spend in the conduit by increasing the velocity of the moving gas, the increased velocity of the moving gas changing the back pressure in the conduit; and
passing the free radicals through at least one of the plurality of other openings and to the surface of the element to remove the debris from the surface of the element without removing the element from the EUV light source.

2. The method of claim 1 , wherein the free radicals remove the debris from the surface of the element by etching.

3. The method of claim 1 , wherein the plurality of other openings comprise openings of different sizes, each passing through the sidewall, and passing the free radicals through the at least one other opening comprises passing the free radicals through the plurality of openings.

4. The method of claim 3 , wherein the smallest of the plurality of openings passing through the sidewall is the opening that is closest to the first opening, and the largest of the plurality of the openings passing through the sidewall is the opening that is farthest from the first opening.

5. The method of claim 4 , wherein the sizes of the plurality of openings increase between the smallest of the plurality of openings and the largest of the plurality of openings.

6. The method of claim 1 , wherein the debris is removed from the surface of the element at a uniform rate.

7. The method of claim 1 , further comprising positioning the at least one other opening defined by the conduit relative to the element.

8. The method of claim 7 , wherein positioning the at least one other opening defined by the conduit relative to the element comprises moving the at least one other opening relative to the element.

9. The method of claim 7 , wherein the at least one other opening is moved in a plane that is parallel to a perimeter of the element.

10. The method of claim 7 , wherein the at least one other opening is rotated relative to a plane that includes a perimeter of the element.

11. The method of claim 1 , wherein directing the free radicals in the conduit toward the at least one other opening comprises creating a pressure differential between a source of the free radicals and the plurality of other openings, with the at least one other opening being at a lower pressure than the source of the free radicals and at a higher pressure than a region outside of the conduit.

12. The method of claim 1 , wherein the free radicals pass through the at least one other opening while the EUV light source is operating.

13. The method of claim 1 , wherein the at least one other opening is in the curved portion of the conduit.

14. A system comprising:
an extreme ultraviolet light source comprising:
a vacuum chamber;
a target material delivery system that directs target material toward a target location in the vacuum chamber, the target location receiving an amplified light beam, and the target material comprising a material that emits extreme ultraviolet light in a plasma state; and
a collector that receives and reflects at least some of the emitted extreme ultraviolet light;

a radical transport system comprising:
a conduit comprising a first opening at a first end of the conduit, a sidewall that defines an inner surface and an outer surface, and a plurality of other openings that pass through the sidewall from the inner surface to the outer surface, the first opening and the inner surface of the conduit comprising a material having a recombination coefficient of 5×10 −3 or less, the recombination coefficient being a measure of the likelihood of a free radical recombining or otherwise attaching to the material, the sidewall of the conduit passing through a wall of the vacuum chamber and positioned with the first opening external to the vacuum chamber and the plurality of openings inside the vacuum chamber and oriented toward the collector, wherein
the outer surface of the conduit comprises a relative amount of open regions formed by the plurality of other openings as compared to an amount of the sidewall, and the relative amount of the open regions as compared to the amount of the sidewall increases along the conduit,
the sidewall of the conduit has an extent of at least 0.8 meters,
the sidewall of the conduit comprises a linear portion and a curved portion,
at least one of the plurality of openings is in the curved portion of the conduit,
the conduit comprises a metallic material, and
the metallic material of the conduit is coated with the material that has a recombination coefficient of 5×10 −3 or less at the inner surface and the first opening; and

a source of free radicals comprising an applicator configured to generate free radicals from microwave energy, the source of free radicals being external to the vacuum chamber, and the applicator of the source of free radicals being coupled to the conduit at the first opening.

15. The system of claim 14 , wherein the relative amount of the open regions as compared to the amount of the sidewall increases along the conduit comprises the openings having different sizes, the smallest of the plurality of openings being closest to the first end of the conduit, and the largest of the plurality of openings being farthest from the first end of the conduit.

16. The system of claim 14 , wherein the conduit is positioned outside of a path of propagation of the amplified light beam.

17. The system of claim 14 , wherein the conduit is configured to move relative to the collector.

18. The system of claim 14 , wherein the radical transport system comprises a plurality of conduits.

19. The system of claim 14 , wherein the perimeter of the collector is curved, and the curved portion of the conduit follows the curved perimeter of the collector.

20. The system of claim 19 , wherein the collector comprises an aperture through which the amplified light beam propagates, and the curved portion of the collector is between the aperture of the collector

Assignees

• Asml Netherlands Bv

Inventors

• De Dea Silvia
• Ershov Alexander I
• Verhoff Brandon
• Wilson Gregory
• La Fontaine Bruno M

Classifications

• G03F7/70033

  by plasma extreme ultraviolet [EUV] sources · CPC title

• G03F7/70925 Primary

  Cleaning, i.e. actively freeing apparatus from pollutants, e.g. using plasma cleaning · CPC title

• H05G2/0094 Primary

  Reduction, prevention or protection from contamination; Cleaning · CPC title

• H05G2/005

  Electricity · mapped topic

• H05G2/008 Primary

  involving an energy-carrying beam in the process of plasma generation · CPC title