Decomposition and Roughness Analysis of Chemically Amplified Molecular Resist for Reducing Line Width Roughness

A molecular resist material, which includes only one protecting group per molecule was designed and synthesized as Prot-1. After confirming the structure and purity of Prot-1, resist A formulated with Prot-1 as a base material was prepared. Resist A showed a good contrast curve. To confirm the decomposition behavior by an electron beam (EB) exposure, resist A was analyzed using high performance liquid chromatography (HPLC). From the HPLC analysis, it was found that the dissolution switching of resist A due to EB exposure was caused by a deprotection reaction of Prot-1. We evaluated the resolution and line edge roughness (LER) of resist A using EB lithography. Resist A showed 25 nm half pitch (hp) resolution and a partially resolved 20 nm hp at an exposure dose of 36 \mbox{$\mu$}C/cm 2 using an EB writing system with an acceleration voltage ($V$) of 50 kV. The LER of resist A was 3.8 nm ($3\sigma$) for a 100-nm-hp line-and-space pattern, which is similar to a ZEP520A non chemically amplified resist. As a result, we confirmed that a uniform deprotection reaction of just one deprotection group of resist A in the exposed area improved LER and resolution.