Recent Development in Molecular Resists for Extreme Ultraviolet Lithography

Extreme ultraviolet (EUV) lithography systems can in principle provide extremely high resolution (line-and-space patterns with less than 22 nm separation) for fabrication of microelectronic devices. For this purpose, various molecular resist materials based on calixarene, low-molecular-weight phenol resins, fullerene, ladder cyclic oligomer (noria), and photo-acid generator-bonding molecules have been investigated, and have provided resist patterns with a resolution of 22-50 nm. Although these molecular glasses have the potential to give higher resolution patterns, their values of line-edge roughness remain too high at present. This review deals with the current status of molecular resists for EUV systems and prospects for further development.