Investigation of capillary bridges growth in NIL process

Abstract

It is well admitted that NanoImprint is a powerfull next generation lithography. Nevertheless many defects may appear during a NanoImprint process. Some of them are clearly related to the stamp or polymer surface properties, or the stamp pattern symmetry breakdown. This paper will address the defectivity issue in imprint process and specially in non printed areas where resist features may appear. They are related to capillary forces between the stamp surface and the polymer. The understanding of their growth with respect to mold-polymer distance and printing process is presented. A specific stamp, with cavity depths ranging from 12-224 nm, has been designed to control the capillary bridge growth. The resulting capillary bridges were characterized as a function of the cavity depth, printing temperature, resist thickness and printing time. Results show that capillary bridge number is strongly influenced by cavity depth and in a less extent by temperature and printing time.