Apparatus and method for generating an electromagnetic radiation

An electromagnetic radiation generation apparatus, comprising:

• a chamber;
• a target material supplier connected to the chamber and configured to supply a target material to an excitation region;
• a light source configured to emit a light beam on the target material in the excitation region to generate plasma and an electromagnetic radiation;
• a collector disposed under the chamber, the collector having a reflection surface configured to reflect the electromagnetic radiation, wherein the collector comprises a plurality of holes arranged in an array including a plurality of rows of holes, and a number of holes in a first row is different from a number of holes in a second row;
• a gas supplier configured to provide a buffer gas;
• and
• a gas pipeline in communication with the gas supplier and the holes of the collector, and configured to purge the buffer gas to the excitation region through the holes of the collector to reduce debris of the target material and plasma by-products from being deposited on the reflection surface of the collector.

An electromagnetic radiation generation apparatus, comprising:

• a chamber;
• a target material supplier connected to the chamber and configured to supply a target material to an excitation region;
• a light source configured to emit a light beam on the target material in the excitation region to generate plasma and an electromagnetic radiation;
• a collector disposed under the chamber, the collector including a plurality of concentric ring structures and a reflection surface configured to collect and reflect the electromagnetic radiation, wherein two adjacent concentric ring structures defines a concentric gap having a ring shape, the two adjacent concentric ring structures are separated by the concentric gap, and the concentric gap extends through a width of the collector in an entire radial portion between the concentric ring structures;
• a gas supplier configured to provide a buffer gas;
• and
• a gas pipeline in communication with the gas supplier and the concentric gaps of the collector, and configured to purge the buffer gas to the excitation region through the concentric gaps of the collector to reduce debris of the target material and plasma by-products from being deposited on the reflection surface of the collector,
• wherein the gas pipeline comprises a plurality of sets of tubelets connected to the plurality of concentric gaps, respectively, and configured to form a turbulence in the excitation region, and the plurality of tubelets corresponding to the same concentric gap are arranged in a spiral swirl pattern.