Advanced mask particle cleaning solutions

The majority of trends in lithography technology necessitate the use of smaller, higher aspect, patterns on photomasks which are increasingly sensitive to traditional cleaning processes. Particle defects are of increasing concern since, in deep and even overhanging structures, they can become fixed to the surface with such strength that any traditional cleaning technique would destroy any small, high-aspect, mask structures. A series of advanced new solutions are presented here which have been shown to remove these types of problem particles as applied to 45 nm node nanomachining mask repair with a RAVE nm450 system. In the first method, a cryogenic cleaning system is modified to greatly enhance selective removal of nanoparticles from high aspect structures. In the second method, the nm450 repair tool itself is applied to selectively remove targeted particles from a nanoscale area of the mask surface thus only affecting the region of interest and not touching any sensitive surrounding surfaces or structures.