Apparatus and method for generating extreme ultraviolet radiation

A target droplet generator for an extreme ultraviolet (EUV) source, the target droplet source comprising:

• a droplet generator configured to generate target droplets of a given material, the droplet generator comprising a nozzle configured to supply the target droplets in a space enclosed by a chamber;
• and
• a sleeve disposed in the chamber proximal to the nozzle, the sleeve configured to provide a path for the target droplets in the chamber, wherein the sleeve has a longitudinally tapering cross-section, the sleeve has a cross-section having a closed shape distal to the nozzle and a cross-section having an open shape proximal to the nozzle.

A method for operating an extreme ultraviolet (EUV) radiation source, the method comprising:

• generating target droplets of a given material in a droplet generator through a nozzle of the droplet generator in a space enclosed by a chamber including an environment;
• and
• providing the target droplets to a zone of excitation through a sleeve disposed in the chamber proximal to the nozzle, wherein the sleeve has a longitudinally tapering cross-section, the sleeve has a cross-section having a closed shape distal to the nozzle and a cross-section having an open shape proximal to the nozzle.