Novel Etch-Resistant Molecular Glass Photoresist Based on Pyrene Derivatives for Electron Beam Lithography.

Novel -butyloxycarbonyl-protected molecular glass photoresists with pyrene as the core (Pyr-8Boc and Pyr-4Boc) were designed and synthesized. The thermal stability and film-forming ability were measured to assess their applicability for lithography. Pyr-Boc (Pyr-8Boc and Pyr-4Boc) photoresists were evaluated by high-resolution electron beam lithography (EBL), acting as chemically amplified resists. Pyr-4Boc showed a better lithography performance, achieving 25 nm line/space patterns at the dose of 50 μC/cm. Under SF/O plasma, the etch selectivity of the Pyr-4Boc photoresist to silicon was 12.3, which is twice that of the commercially available poly(methyl methacrylate) photoresist (950 k). The lithography mechanism of EBL was further investigated. Theoretical calculations of HOMO/LUMO orbital energies, cyclic voltammetry, and fluorescence quenching experiments were conducted to confirm the electron-transfer reactions between the Pyr-Boc and photoacid generator. The study provides an option of high sensitivity and etch-resistant photoresist for EBL.