Negative EUV Resist Based on Thiol-Ene System

Non-conventional chemically amplified (CA) resist was designed. Photo-induced thiol/ene radical reaction was used to insolubilize the resist based on difunctional thiol and poly(4-hydroxystyrene) (PHS) derivatives. Hydroxy groups of PHS were modified with allyl or propargyl moiety. Dissolution property of the modified-PHS in TMAHaq solution was affected by the modification degree. Resist was prepared by mixing the modified-PHS, difunctional thiol compound, and photoradical generator. Photosensitivity of the resist was studied using 254- and 13.5-nm light. The sensitivity was strongly affected by the modification degree of PHS, molecular weight of PHS, molecular weight distribution of PHS, and amounts of thiol compound and photoradical generator added. Outgassing of the present system was studied by the pressure rise analysis. It was found that the present resist system was highly sensitive to EUV exposure.