Development of a technique for rapid at-wavelength inspection of EUV mask blanks

We have dramatically increased the sensitivity of a technique for the rapid inspection of EUV multilayer-coated mask blanks. In this technique an EUV sensitive resist is applied directly to a mask blank which is then flood exposed with EUV light and partially developed. Reflectivity defects in the mask blank result in mounds in a partially developed positive resist that appear as high contrast objects in a standard Nomarski microscope. The use of a higher contrast resist is shown experimentally to result in the creation of dramatically taller mounds. A simple model for the exposure and development of the resist has been developed and the predictions of the model compare well with the experimental results.