Photo-deprotection resist based on photolysis of o-nitrobenzyl phenol ether: challenge to half-pitch 22 nm using near-field lithography

摘要

We propose a non chemically-amplified positive-tone photoresist based on photolysis of o-nitrobenzyl phenol ether (NBP). The increase in the amount of the phenolic hydroxyl group just after the exposure to the i-line propagation light is observed via IR spectroscopy. Using near-field lithography (NFL) combined with the NBP, we form half-pitch (hp) 32 nm line and space (L/S) patterns with lower line edge roughness (LER) than those of a chemically amplified resist (CAR). The high-resolution feature of the NBP is attributed to the photoreaction system without the acid diffusion, which is inherently involved in CARs, although the NBP requires six times as much exposure dose as the CAR does. A Hp 32 nm L/S patterns with 10 nm depths are successfully transferred to the 100 nm thick bottom-layer resist through the tri-layer resist process. Hp 22 nm L/S patterns with 10 nm depths are also fabricated on the top portion of a single-layer of NBP.