| Abstract: | A method and an apparatus to protect a reticle against particles and
chemicals in an actinic EUV reticle inspection tool are presented. The
method and apparatus utilizes a pair of porous metal diffusers in the
form of showerheads to provide a continual flow of clean gas. The main
showerhead bathes the reticle surface to be inspected in smoothly
flowing, low pressure gas, isolating it from particles coming from
surrounding volumes. The secondary showerhead faces away from the reticle
and toward the EUV illumination and projection optics, supplying them
with purge gas while at the same time creating a buffer zone that is kept
free of any particle contamination originating from those optics. |