Multibenzyl Chloride Based Molecular Resists Enabling 13 nm Half-Pitch Lithography via Self-Cross-Linking

We developed a negative-tone resist platform based on multibenzyl chloride modified molecular glasses with low molecular weight (<800 Da) to address the resist challenges of electron beam lithography (EBL) and extreme ultraviolet lithography (EUVL). A series of molecular glasses with different substitution positions of the chloromethyl group (designated as AD4xCl, x = O, M, and P, representing the ortho-, meta-, and para-substitution, respectively) were designed and synthesized, and their resists’ lithographic performance was evaluated. The thermal analysis, film-forming capability, and solubility measurements demonstrate the potential of AD4xCl as a negative-tone non-chemically amplified resist (n-CAR) material. Feature sizes as small as 16 nm half-pitch (HP) were achieved using EBL, and a significant effect of the substitution positions on the resolution and sensitivity was observed. Atomic force microscopy (AFM) with peak force quantitative nanomechanical mapping mode measurement confirmed that the difference in substituent positions significantly affects the self-cross-linking efficiency and mechanical strength of the resist films, which is the main reason for the differences in sensitivity and resolution limits. The meta-substituted AD4MCl molecule resist exhibited the best performance and was further investigated by EUVL, achieving an impressive 13 nm pattern with a line edge roughness (LER) of 2.6 nm at an exposure dose of 137.9 mJ cm–2. In situ mass spectrometry and X-ray photoelectron spectroscopy (XPS) showed that the EUV-induced self-cross-linking of multibenzyl radicals among the AD4MCl molecules drives the solubility switch, enabling high-resolution negative-tone patterning.