A Core structural design strategy for molecular resists based on inhibiting acid diffusion and reducing deprotection stochasticity
Abstract
As lithographic resolution improves, stochastic effects during the lithography process have become increasingly significant in influencing pattern quality. Compared to polymeric resists, Single-molecule resins (SMRs), also known as molecular glasses, exhibit potential for mitigating development stochasticity due to their smaller molecular size and monodisperse nature. This study aims to investigate the relationship between the core structure of SMRs and their lithographic stochastic effects. To this end, we designed a series of bisphenol-A-like SMRs with core structures of adamantane-diyl, isopropylidene and isopropylidene, namely AD-Boc, BPA-Boc, and PH-Boc. Performance evaluations revealed the ranking in terms of LER and contrast: AD-Boc > BPA-Boc > PH-Boc. Fourier-transform infrared spectroscopy (FTIR) and X-ray reflectivity (XRR) analyses demonstrated that AD-Boc exhibits the strongest capability to suppress acid diffusion. Furthermore, calculations of the critical deprotection ratio combined with surface energy measurements confirm that AD-Boc induces the least stochasticity during development. These two effects together account for the observed differences in final lithographic performance. This work elucidates how the core structure of SMRs modulates lithographic performance by controlling acid diffusion and development stochasticity, providing valuable insights for the design of next-generation photoresists.
