A laser-plasma EUV radiation source (10) that employs one or more approaches
for preventing vaporization of material from a nozzle assembly (40) of the
source (10) by electrical discharge from the plasma (30). The first
approach includes employing an electrically isolating nozzle end, such as a glass
capillary tube (46). The tube (46) extends beyond all of the conductive
surfaces of the nozzle assembly (40) by a suitable distance so that the
pressure around the closest conducting portion of the nozzle assembly (40)
is low enough not to support arcing. A second approach includes providing electrical
isolation of the conductive portions of the source (40) from the vacuum
chamber wall. A third approach includes applying a bias potential (52) to
the nozzle assembly (40) to raise the potential of the nozzle assembly (40)
to the potential of the arc.
