Extreme ultraviolet light generation system utilizing a pre-pulse to create a diffused dome shaped target

A system for generating extreme ultraviolet light by irradiating a target with a pre-pulse laser beam and a main laser beam to turn the target into plasma, the system comprising:

• a chamber;
• a target supply configured to supply the target to a region inside the chamber;
• a first laser apparatus configured to output the pre-pulse laser beam having a pulse duration of smaller than 1 ns, the pre-pulse laser beam having a fluence equal to or lower than a fluence of the main pulse laser beam, the fluence of the pre-pulse laser beam being equal to or higher than 6.5 J/cm2 and equal to or lower than 52 J/cm2, where the target is to be irradiated with the pre-pulse laser beam;
• a second laser apparatus configured to output the main pulse laser beam, where the target irradiated with the pre-pulse laser beam is to be further irradiated with the main pulse laser beam;
• and
• an intensity distribution control optical system for controlling intensity distribution of the pre-pulse laser beam so that the pre-pulse laser beam has a uniform intensity distribution region in a first cross-section where the target is irradiated with the pre-pulse laser beam, the first cross-section being perpendicular to a first traveling path of the pre-pulse laser beam, wherein:
• the first laser apparatus is configured to output the pre-pulse laser beam so as to make the target be diffused in a dome shape,
• the uniform intensity distribution region of the first cross-section of the pre-pulse laser beam has an area larger than an area of a maximum cross section of the target, the maximum cross section of the target being perpendicular to the first traveling path, and
• the main pulse laser beam does not have a uniform intensity distribution region in a second cross-section where the target is irradiated with the main pulse laser beam, the second cross-section being perpendicular to a second traveling path of the main pulse laser beam.