System, method and apparatus for target material debris cleaning of EUV vessel and EUV collector

An extreme ultraviolet (EUV) light source comprising:

• an EUV vessel having an EUV purge gas inlet, the EUV purge gas inlet being configured to be coupled to a purge gas source for dispensing a quantity of purge gas into the EUV vessel;
• an EUV collector disposed in the EUV vessel, the EUV collector having a reflective surface;
• a target material source for dispensing a quantity of target material into the EUV vessel;
• a first source of hydrogen radicals disposed within the EUV vessel, the first source comprising a capacitively coupled hydrogen plasma chamber, the capacitively coupled hydrogen plasma chamber comprising:
• a first hydrogen source inlet configured to be coupled to a source of hydrogen;
• a first hydrogen source electrode configured to be coupled to a first RF signal source;
• a second hydrogen source electrode configured to be coupled to a second RF signal source, the first hydrogen source electrode and the second hydrogen source electrode being arranged to produce the hydrogen radicals in the hydrogen from the source of hydrogen in a space between the first hydrogen source electrode and the second hydrogen source electrode, and
• a first hydrogen radical source outlet disposed to cause the hydrogen radicals to flow across at least a portion of the reflective surface of the EUV collector,
• wherein during operation of the EUV light source hydrogen radicals dispensed from the first hydrogen radical source outlet combine with at least a portion of a target material debris deposit disposed on the portion of the reflective surface of the EUV collector to generate a volatile compound;
• and
• an EUV vessel purge outlet for passing the volatile compound out of the EUV vessel.