Mechanisms of acid generation from ionic photoacid generators for extreme ultraviolet and electron beam lithography.

Photoacid generators (PAGs) are important components of chemically amplified resists. The properties of PAGs directly affect the sensitivity of photoresists, line edge roughness, and resolution. Understanding the photoacid generation process in extreme ultraviolet (EUV) and electron beam (EB) lithography is helpful for photoresist design. However, the microscopic mechanisms remain largely unclear and the large variety in the molecular structure of PAGs presents a challenge to overcome. In this work, we investigate the microscopic processes of photoacid production of ionic PAGs for EUV and EB lithography. The PAG dissociation pathway is found to depend on the molecular structure and conformations. The processes of photoacid production and by-product generation are also revealed. The results contribute to a better understanding of the photochemical reactions in EUV and EB lithography, providing insights into the molecular design of novel PAGs and photoresists.