Pixelated chemically amplified resists: Investigation of material structure on the spatial distribution of photoacids and line edge roughness

Preorganized pixel-forming photoresists were prepared to investigate the effect of well-defined material structures and the spatial distribution of photoacid on line edge roughness of chemically amplified photoresists. Asymmetric poly(styrene)-block-poly(⁠$t$-butylacrylate) $(PS-b-PtBA)$ diblock copolymers, which formed PS cylinders or spheres within a $PtBA$ matrix, were used as photoresists by adding catalytic amounts of photoacid generators (PAGs). PAGs resided only in the $PtBA$ matrix domain, resulting in the PAG chemistry occurring only in the matrix domain. The pixelated photoresists showed a significant solubility switch after UV or x-ray exposure and postexposure bake, such that the polymer in the exposed regions dissolved in aqueous base solution. Granular structures that were matched with the domain spacing and structure of the block copolymer photoresists were observed on the edge of the patterned features. This model system demonstrated that line edge roughness is directly correlated to the structure of pixelated photoresist materials.