Apparatus for and method of source material delivery in a laser produced plasma EUV light source

Patent metadata

Field	Value
Publication number	US-9795023-B2
Application number	US-201615048708-A
Country	US
Kind code	B2
Filing date	Feb 19, 2016
Priority date	Dec 2, 2013
Publication date	Oct 17, 2017
Grant date	Oct 17, 2017

Abstract

A device and method are disclosed in which gas is caused to flow parallel to a flow of source material to form a gas shroud. The gas shroud may protect flow of source material from being disrupted by a cross flow of gas. The gas shroud may also limit heating of a physical shroud through which the source material passes and limit accumulation of source material on the physical shroud by deforming a plasma bubble formed during irradiation of the source material so that the plasma bubble does not come too near the physical shroud. A device and method are also disclosed for establishing an additional transverse flow of gas so that the gas shroud does not cause source material contamination of an optic used to collect light generated during irradiation of the source material.

First claim

What is claimed is:

1. A device comprising:
a chamber;
an EUV optic located within the chamber;
a source material delivery system having a source material release point and adapted to deliver a stream of source material to an irradiation region within the chamber along a path between the source material release point and the irradiation region;
a first gas delivery system adapted to cause gas to flow in the chamber along at least a portion of the path; and
a second gas delivery system adapted to cause gas to flow from the EUV optic and towards the irradiation region, the second gas delivery system comprising a first gas delivery line arranged adjacent a first portion of a substantially radially symmetric surface of the EUV optic confronting the irradiation region and extending substantially radially at least part of a distance between a central aperture in the EUV optic and an outer circumferential edge of the EUV optic and a second gas delivery line arranged adjacent a second portion of the substantially radially symmetric surface of the EUV optic confronting the irradiation region and extending substantially radially at least part of a distance between the central aperture in the EUV optic and the outer circumferential edge of the EUV optic, said second gas delivery line being arranged symmetrically across the central aperture from the first gas delivery line in an opposed spoke-like arrangement.

2. A device as recited in claim 1 wherein the source material delivery system includes a solid shroud extending from the source material release point and parallel the path to a solid shroud end to protect at least a portion of the stream, and wherein the first gas delivery system is adapted to cause gas to flow along at least a portion of the path between the solid shroud end and the irradiation region.

3. A device as recited in claim 2 wherein the first gas delivery system is adapted to cause gas to flow in the chamber along at least a portion of the path to force a plasma bubble formed around the irradiation region when the source material in the stream is irradiated away from the solid shroud end.

4. A device as recited in claim 2 wherein the first gas delivery system is adapted to cause gas to flow in the chamber along at least a portion of the path inside the solid shroud and out of the solid shroud end towards the irradiation region.

5. A device as recited in claim 2 wherein the solid shroud has a length parallel to the path and the first gas delivery system is adapted to cause gas to flow in the chamber outside of the solid shroud and parallel to the length of the solid shroud and towards the irradiation region.

6. A device as recited in claim 1 wherein a flow rate at which the first gas delivery system is adapted to cause gas to flow in the chamber along at least a portion of the path such that the flow of gas from the second gas delivery system does not cause the stream to deviate substantially from the path.

7. A device as recited in claim 1 wherein the EUV optic comprises a collector mirror.

8. A device as recited in claim 1 wherein the second gas delivery system is adapted to cause gas to flow through a central aperture in the EUV optic.

9. A device comprising:
a chamber having an irradiation region within;
a EUV optic with a central aperture;
a source material delivery system having a source material release point within the chamber and adapted to deliver a stream of source material to the irradiation region along a path between the source material release point and the irradiation region, the source material delivery system comprising a solid shroud extending from the source material release point and parallel to the path to a solid shroud end to protect at least a portion of the stream;
a first gas delivery system in fluid communication with an interior of the chamber and adapted to cause gas to flow through the central aperture and towards the stream; and
a second gas delivery system in fluid communication with the interior of the chamber and adapted to cause gas to flow in the chamber toward the irradiation region and along at least a portion of the path, the second gas delivery system comprising a first gas delivery line arranged adjacent a first portion of a substantially radially symmetric surface of the EUV optic confronting the irradiation region and extending substantially radially at least part of a distance between a central aperture in the EUV optic and an outer circumferential edge of the EUV optic and a second gas delivery line arranged adjacent a second portion of the substantially radially symmetric surface of the EUV optic confronting the irradiation region and extending substantially radially at least part of a distance between the central aperture in the EUV optic and the outer circumferential edge of the EUV optic, said second gas delivery line being arranged symmetrically across the central aperture from the first gas delivery line in an opposed spoke-like arrangement.

10. A method comprising the steps of:
directing a stream of source material along a path between a source material release point in a chamber and an irradiation region in the chamber;
streaming gas in the chamber along at least a portion of the path; and
a step concurrent with the streaming step of causing gas to flow from the direction of an EUV optic and towards the path by causing gas to flow into the chamber using a first gas delivery line arranged adjacent a first portion of a substantially radially symmetric surface of the EUV optic confronting the irradiation region and extending substantially radially at least part of a distance between a central aperture in the EUV optic and an outer circumferential edge of the EUV optic and a second gas delivery line arranged adjacent a second portion of the substantially radially symmetric surface of the EUV optic confronting the irradiation region and extending substantially radially at least part of a distance between the central aperture in the EUV optic and the outer circumferential edge of the EUV optic, said second gas delivery line being arranged symmetrically across the central aperture from the first gas delivery line in an opposed spoke-like arrangement.

11. A method as recited in claim 10 wherein the source material delivery system includes a solid shroud extending from the source material release point and parallel the path to a solid shroud end to protect at least a portion of the stream, and wherein the streaming step comprises streaming gas along at least a portion of the path between the solid shroud end and the irradiation region.

12. A method as recited in claim 11 further comprising a step of irradiating the source material causing a plasma bubble to form and wherein the streaming step comprises causing gas to force the plasma bubble away from the solid shroud end.

13. A method as recited in claim 11 wherein streaming step comprises causing gas to flow in the chamber along at least a portion of the path inside the solid shroud and out of the solid shroud end towards the irradiation region.

14. A method as recited in claim 11 wherein the solid shroud has a length parallel to the path and wherein the streaming step comprises causing gas to flow in the chamber outside of the solid shroud and parallel to the length of the solid shroud and towards the irradiation region.

15. A method as recited in claim 10 wherein said streaming step comprises streaming gas at a flow rate large enough that the flow of gas from the direction of an EUV optic and towards the path does not prevent the source material from passing through the irradiation region.

Assignees

• Asml Netherlands Bv

Inventors

• Ershov Alexander I
• Evans David
• Graham Matthew

Classifications

• H05G2/008

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

• H05G2/003

  the plasma being generated from a material in a liquid or gas state · CPC title

• H05G2/0027 Primary

  Arrangements for controlling the supply; Arrangements for measurements · CPC title

• G03F7/70033

  by plasma extreme ultraviolet [EUV] sources · CPC title

• H05G2/0094

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