Techniques for removal of contamination from EUVL mask without surface damage

Mask defectivity is an acknowledged road block for the introduction of EUV lithography (EUVL) for manufacturing. There are significant challenges to extend the conventional methods of cleaning developed for standard 193nm optical photomask to meet the specific requirements for EUV mask structure and materials. In this work, the use of UV activated media for EUV mask surface cleaning is evaluated and the effects on Ru capping layer integrity are compared against conventional cleaning methods. Ru layer surface is analyzed using roughness measurements (AFM) and reflectivity changes (EUV-R and optical).