Radiation-Sensitive Resin Composition for High-Aspect-Ratio Resist Uniformity

The patent applies local quality by selectively fluorinating only specific positions in the sulfonic acid structure (using compounds of formula (1) where R4-R8 are specific combinations of H, F, and fluorinated hydrocarbon groups) rather than complete perfluorination. This localized fluorination at key positions maintains the necessary acidity and photoacid generator functionality while reducing overall environmental harm associated with extensive fluorination.

The patent changes the chemical structure parameters of the photoacid generator by using compounds of formula (1) with specific substituent patterns (where at least one of R4-R8 is a fluorinated hydrocarbon group and others are H or fluorinated hydrocarbon groups). This structural parameter modification allows tuning of both environmental compatibility and photoacid generator performance, resolving the contradiction between sensitivity and environmental compatibility.

The patent introduces an acid diffusion controlling agent (compound of formula (7) with specific nitrogen-containing structures) as an intermediary substance that mediates between the photoacid generator and the resin. This intermediary controls acid diffusion during the exposure process, enabling uniform pattern formation even at high aspect ratios by preventing excessive acid migration that would otherwise compromise pattern uniformity and circularity.

The patent creates a composite resist composition containing multiple functional components: the onium salt compound (photoacid generator), the resin (polymer matrix), and the acid diffusion controlling agent. This composite material system works synergistically to achieve both high aspect ratio patterns and maintained uniformity/circularity, as each component contributes specific functionality that compensates for the limitations of the others.