Lithographic apparatus and device manufacturing method

A device manufacturing method comprising:

• providing a beam of radiation;
• patterning the beam of radiation;
• projecting the patterned beam of radiation onto a target portion of a layer of radiation-sensitive material;
• providing a flow of gas in a downstream radical source to produce a beam of radicals;
• and
• directing said beam of radicals onto a surface to be cleaned.

A lithographic projection apparatus comprising:

• a radiation source that provides a beam of radiation;
• a support structure constructed to support a patterning structure, said patterning structure adapted to pattern the beam of radiation according to a desired pattern;
• a substrate holder constructed to hold a substrate;
• a projection system constructed and arranged to project the patterned beam onto a target portion of the substrate;
• a radical source connected to a gas supply and configured to provide a localized beam of radicals;
• and
• a structure to direct said beam of radicals onto a surface to be cleaned,
• wherein said radical source is disposed away from said radiation source such that operating conditions of said radical source do not adversely affect said beam of radiation.