An DPP EUV source is disclosed which may comprise a debris mitigation
apparatus employing a metal halogen gas producing a metal halide from
debris exiting the plasma. The EUV source may have a debris shield that
may comprise a plurality of curvilinear shield members having inner and
outer surfaces connected by light passages aligned to a focal point,
which shield members may be alternated with open spaces between them and
may have surfaces that form a circle in one axis of rotation and an
ellipse in another. The electrodes may be supplied with a discharge pulse
shaped to produce a modest current during the axial run out phase of the
discharge and a peak occurring during the radial compression phase of the
discharge. The light source may comprise a turbomolecular pump having an
inlet connected to the generation chamber and operable to preferentially
pump more of the source gas than the buffer gas from the chamber. The
source may comprise a tuned electrically conductive electrode comprising:
a differentially doped ceramic material doped in a first region to at
least select electrical conductivity and in a second region at least to
select thermal conductivity. The first region may be at or near the outer
surface of the electrode structure and the ceramic material may be SiC or
alumina and the dopant is BN or a metal oxide, including SiO or
TiO.sub.2. The source may comprise a moveable electrode assembly mount
operative to move the electrode assembly mount from a replacement
position to an operating position, with the moveable mount on a bellows.
The source may have a temperature control mechanism operatively connected
to the collector and operative to regulate the temperature of the
respective shell members to maintain a temperature related geometry
optimizing the glancing angle of incidence reflections from the
respective shell members, or a mechanical positioner to position the
shell members. The shells may be biased with a voltage. The debris shield
may be fabricated using off focus laser radiation. The anode may be
cooled with a hollow interior defining two coolant passages or porous
metal defining the passages. The debris shield may be formed of
pluralities of large, intermediate and small fins attached either to a
mounting ring or hub or to each other with interlocking tabs that provide
uniform separation and strengthening and do not block any significant
amount of light.