Laser-produced plasma EUV light source with pre-pulse enhancement

An extreme ultraviolet (EUV) radiation source for generating EUV radiation, said source comprising:

• a device for generating at least one stream of a target material, said target material being directed towards a target area;
• and
• a system for generating a main pulse laser beam and a pre-pulse laser beam, wherein the main pulse beam and the pre-pulse beam are timed so that the pre-pulse beam arrives at the target area before the main pulse beam, and wherein the pre-pulse beam generates a weakly ionized plasma at the target area and the main pulse beam generates the EUV radiation, and wherein the main pulse beam and the pre-pulse beam impinge the target area at an angle of 30° or greater between the beams, and wherein the pre-pulse beam arrives at the target area in the range of 20–200 ns before the main pulse beam.

An extreme ultraviolet (EUV) radiation source for generating EUV radiation, said source comprising:

• a device for generating at least one stream of a target material, said target material being directed towards a target area;
• and
• a system for generating a main pulse laser beam and pre-pulse laser beam, wherein the main pulse beam and the pre-pulse beam are timed so that the pre-pulse beam arrives at the target area before the main pulse beam, and wherein the pre-pulse beam generates a weakly ionized plasma target area and the main pulse beam generates the EUV radiation, and wherein the main pulse beam and the pre-pulse beam are separate by an angle of 30° or greater at the target area, and wherein the pre-pulse beam has an energy of about 40 mJ and a duration of about 10 ns and the main pulse beam has an energy of about 700 mJ and a duration of about 10 ms.