As the design rule continues to shrink towards 3x nm and below, lithographers are searching for new and
advanced methods of mask lithography such as immersion, double patterning and extreme ultraviolet
lithography (EUVL). EUV lithography is one of the leading candidates for the next generation lithography
technologies after 193 nm immersion and many mask makers and equipment makers have focused on
stabilizing the process. With EUV lithography just around the corner, it is crucial for advanced mask makers
to develop and stabilize EUV mask processes. As a result, an inspection tool is required to monitor and
provide quick feedback to each process step.