Pattern inspection of EUV mask using a EUV microscope

It is proposed that at-wavelength EUV mask inspection system based on EUV microscope, which is the best way to observe the mask directly. Using this system, preliminary experiments to examine the pattern inspection of EUVL mask is carried out. EUV microscope has a capability to resolve 50 nm lithographic node finished EUVL mask. We confirmed that at-wavelength microscope rather than SEM is both powerful and useful for evaluating the mask fabrication process for EUVL. Furthermore, it is find out that the contrast of the mask images observed by EUVM influenced by the absorber material. As the result, important information of the finished EUVL mask can be obtained utilizing EUVM, which is very important tool for the finished EUVL mask inspection.