Advances in TFE-based fluoropolymers for 157-nm lithography: a progress report

Significant progress has been made in 157 nm resist technology. Material development for this emerging field is continuing at a frantic pace. Many new and interesting polymers are surfacing for these studies. Fluorine-containing polymers have become the prominent platform for a variety of research activities within this field and a tremendous amount of progress has been achieved. Since the absorbance of a variety of different organic polymers at 157 nm was first reported, a vast array of fluorine-containing materials has been proposed and designed for photolithography at this wavelength. Free radical polymerizations, metal-catalyzed addition polymerizations and metal-catalyzed copolymerizations with carbon monoxide have produced materials that have yielded positive-tone images with 157 nm exposures. Major progress has been made in decreasing the absorbance of fluoropolymers based on Tetra Fluoro Ethylene (TFE). A number of key monomers have been synthesized based on the learning this project has cataloged over the past 2-½ years. Development of these new and interesting monomers has been done with copolymerizations of TFE taken into consideration. Our project has focused on polymer synthesis efforts, learning how to maximize transparency at 157 nm with consideration to etch resistance and imaging properties of these materials. Vacuum-UV (VUV) studies and variable angle spectroscopic ellipsometry (VASE) data will be shown on numerous fluorinated compounds and synthesized polymers. Our most recent materials have an absorbance of less than 1/μm and etch resistance equal to first generation KrF materials. This paper will provide synthesis, imaging and etch studies that have been completed using a 0.60NA and 0.85NA 157nm micro exposure system.