In current optical lithography, resolution is required to reach for 45 nm half-pitch and a chemically amplified resist (CAR) is used for a wide variety of applications. For ArF lithography beyond the 45 nm half-pitch, it is important to control pattern quality. The molecular design of a photo acid generator (PAG) is very important in the study to control not only acid strength but also acid diffusion length. Various novel PAGs that have different characteristics were synthesized for resist performance improvement. Acid molecular size was determined by molecular orbital (MO) calculation, and the acid diffusion coefficients (D) of these PAGs were evaluated by a bilayer method. As a result, it was found that acid diffusion coefficient (D) could not be controlled simply by adjusting anion molecular size. It may be presumed that the molecular interaction between acid generated by the exposure and polymer matrix areas is one of the most important key factors for controlling acid diffusion.
Preparation of an
unzipping polyester is reported. The monomer
was prepared from benzoic acid in a four-step sequence. Step growth
polymerization of the monomer provides the target polymer. Efficient
depolymerization upon irradiation at 254 nm was confirmed with a quantum
yield of >0.8. The photolysis mechanism was investigated, and the
results of radical trapping experiments are consistent with an initial
Norrish type I like homolysis followed by a radical mediated depropagation
reaction driven by aromatization.
The effects of acid generation efficiency and other properties on the resolution, line width roughness (LWR), and sensitivity (RLS) tradeoff for extreme ultraviolet (EUV) photoresists were evaluated under electron beam (EB) exposure. The acid generators (AGs) introducing a trifluoromethyl group as an electron-withdrawing group on the sulfur atom had a much higher reduction potential than current AGs. We determined acid generation efficiency by the 13 C-NMR method and standard titration. The dissolution inhibitory effect on the alkaline developer and the thermal property of the resist film using each AG were also evaluated. The RLS performance of resists containing AGs with a higher acid generation efficiency than conventional AGs was characterized using the relative Z -factor under EB exposure. #
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