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

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.

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.