A New Photochemical Selective Silylation Technique for Resist Materials

A new selective photochemlcal silylation technique for resist materials has been developed. When deep-UV light is irradiated on resist films in either the vapor- or liquid-phase of monochloroalkylsilanes, many commercially available resist materials, both those that have phenolic hydroxy groups like DNQ/novolak and those that do not like polymethylmethacrylate (PMMA), can be sufficiently silylated. The silylated resist layer shows marked improvement in its durability against O2 dry etching. The silylation mechanism is presumed to be that alkylsilane radicals are firstly generated by deep-UV light irradiation, then the radicals diffuse into the resist film and chemically incorporate with the functional base radicals of the resist that are also generated by deep-UV light irradiation. The mechanism is clearly different from conventional one where the diffusion of the silylating agent is carried out after the UV-light irradiation.