Incorporation of chemical amplification in dual insolubilization resists

Acid diffusion in chemically amplified resists (CARs)—currently the standard resists for semiconductor device manufacturing—is a significant concern in the development of highly resolving resists. However, non-CARs are generally less sensitive to radiation than CARs owing to the lack of an amplification mechanism. Recently, a negative non-CAR utilizing a polarity change and radical crosslinking (a dual insolubilization resist) was proposed. In this study, an acid-reactive compound was introduced into organotin-containing dual insolubilization resists to improve their sensitivity. The synthesized resists were composed of triarylsulfonium cations as a polarity changer and a radical generator; 2-hydroxy-2-methylpropiophenone as a radical generator; triphenyl(4-vinylphenyl)stannane as an EUV absorption enhancer and a quencher; and 4-[(2,4-dimethoxyphenyl)hydroxymethyl]phenylmethacrylate (ARMA) as a polymer-bound acid-reactive unit. By the incorporation of ARMA, the sensitivity to EUV radiation was increased 2.4-fold (the exposure dose required for insolubilization was decreased by approximately 60%). The increased sensitivity is considered to have been caused by the acid-catalytic etherification of ARMA through dimerization and/or with 2-hydroxy-2-methylpropiophenone units. In the 125 keV electron beam (EB) patterning, the organotin-containing dual insolubilization resist with ARMA showed 25 nm half-pitch resolution with 2.1 nm line width roughness at a sensitivity of 160 μC cm−2 (approximately 90 μC cm−2 for a 50 keV EB).