Nonchemically-Amplified Molecular Resists Based on Calixarene Derivatives Enabling 14 nm Half-Pitch Nanolithography

We developed single-component nonchemically-amplified resists (n-CARs) based on calixarene derivatives for high-resolution nanopatterning with electron beam lithography (EBL) and extreme ultraviolet lithography (EUVL). The calixarene derivatives decorated with 2 and 4 photosensitive sulfonium groups (C2S and C4S, respectively) were synthesized and characterized. Both derivatives exhibit excellent thermal stability and film-forming properties, making them suitable as resist materials. A comparative EBL study reveals that C2S resist exhibits superior lithographic performance. The presence of hydrogen bonds between C2S molecules enhances the mechanical strength and the Young's modulus of the resist film, effectively mitigating pattern collapse. The C2S resist achieved an 18 nm line/space (L/S) pattern and a 14 nm L/2S semi-dense pattern with EBL. Performance studies with EUVL yielded an impressive 14 nm half-pitch (HP) pattern with a remarkably low line-edge roughness (LER) of 1.7 nm. Extensive studies of the EUV exposure mechanism, conducted using in-situ quadrupole mass spectrometry (QMS) and X-ray photoelectron spectroscopy (XPS), demonstrated that the solubility switch of the resist material depends on the decomposition of the sulfonium groups and triflate anions.