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초록

The fabrication of protective layers on graphite faces a fundamental dilemma because high-quality, dense films are required to withstand the harsh plasma environments of extreme ultraviolet lithography (EUVL) applications, yet forming such robust coatings without damaging the graphite remains highly challenging. In this study, uniform and dense SiNx ultrathin films for the EUV pellicle are formed on graphite using mild, plasma-sequence-engineered atomic layer deposition, without any damage to graphite. Si2Cl6 is used as the precursor, NH3 plasma as the prime reactant, and sequential N2 plasma as a promoting reactant. The SiNx film fabricated using NH3 plasma, followed by N2 plasma, exhibits a mass density of 3.07 g/cm3, close to the bulk density, with low O and H concentrations. The film exhibits an improved wet-etching resistance against 30 wt.% KOH for 16 h and 250 W H2 plasma for 5 min, mimicking the EUVL environment. Therefore, the optimized SiNx ultrathin film (5 nm) formed on graphite effectively protects graphite against H2 plasma for high-performance EUV pellicles. Furthermore, the mass spectra of the byproducts, such as HCl, reveal the reason for the densification by N2 plasma, while the correlation between film properties and etch resistances is statistically validated through a permutation test.

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