Biodegradability, Cytotoxicity, and Physicochemical Treatability of Two Novel Perfluorooctane Sulfonate-Free Photoacid Generators

Abstract

There is a need for effective, environmentally compatible photoacid generators (PAGs) for application in photolithography for microelectronic device fabrication. Perfluoroalkyl sulfonates (PFAS) used in conventional PAG formulations, such as perfluorooctane sulfonate (PFOS), are under increasing scrutiny due to their widespread environmental distribution and toxicity. Recently, two new PFAS-free, PAG anions with semifluorinated sulfonate anions containing biomolecules (γ-butyrolactone or D-glucose groups) were successfully applied as PAGs. In this study, the biodegradation potential, cytotoxicity, and physicochemical treatability of the new PAG anions was evaluated. PFOS and perfluorobutane sulfonate (PFBS) were used as reference materials in all of the assays. The new PAGs were susceptible to partial degradation by microorganisms in aerobic activated sludge, and these were also readily removed by chemical oxidative treatment with Fenton's reagent [H(2)O(2)/Fe(II)]. In contrast, the compounds were resistant to microbial and chemical attack under reductive conditions as indicated by the low removal efficiencies observed with anaerobic biodegradation assays and chemical assays with zero-valent iron, respectively. The enhanced biodegradation potential and treatability make of the new PAGs attractive materials to resolve current issues related to the lithographic performance and environmental concerns.

Photochemical Fragmentation of Irgacure PAG 103

“…Nonionic PAGs include oxime sulfonates, − oxime esters, and N -sulfonyloxyimides . The choice of PAG for an application depends upon many factors such as the wavelength of radiation, − quantum efficiency of acid generation, solubility in the casting solvent, thermal and hydrolytic stability, toxicity, strength of the liberated acid, − line width, acid diffusion, and environmental considerations. , Although the mechanism of the photochemical decomposition of Crivello salts has been studied, − less is known about how nonionic PAGs release acid. In this paper, a commercial UV light PAG called Irgacure PAG 103 − is examined and key photochemical decomposition products are characterized.…”