Climate-driven redistribution of tuna threatens to disrupt the economies of Pacific Small Island Developing States (SIDS) and sustainable management of the world’s largest tuna fishery. Here we show that by 2050, under a high greenhouse gas emissions scenario (RCP 8.5), the total biomass of three tuna species in the waters of ten Pacific SIDS could decline by an average of 13% (range = −5% to −20%) due to a greater proportion of fish occurring in the high seas. The potential implications for Pacific Island economies in 2050 include an average decline in purse-seine catch of 20% (range = −10% to −30%), an average annual loss in regional tuna-fishing access fees of US$90 million (range = −US$40 million to –US$140 million) and reductions in government revenue of up to 13% (range = −8% to −17%) for individual Pacific SIDS. Redistribution of tuna under a lower-emissions scenario (RCP 4.5) is projected to reduce the purse-seine catch from the waters of Pacific SIDS by an average of only 3% (range = −12% to +9%), indicating that even greater reductions in greenhouse gas emissions, in line with the Paris Agreement, would provide a pathway to sustainability for tuna-dependent Pacific Island economies. An additional pathway involves Pacific SIDS negotiating within the regional fisheries management organization to maintain the present-day benefits they receive from tuna, regardless of the effects of climate change on the distribution of the fish.

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The development of robust, high resolution, positive-and negative-tone resists is necessary for the eventual implementation of DUV lithography in a manufacturing environment. Great progress has been made in the last two years in the area of chemically amplified resists. Environmentally stable, high resolution and high thermal resistance negative-tone resists have been commercially available for three years. Prototype DUV positive-tone resists are now achieving better environmental stability through the use of partially blocked poly(pvinyl)phenol polymer and photoacid generators (PAG) based on organic onium salts. In this paper, our studies of various PAG structures in positive-tone DUV resists are reported. The PAG structure, M+ X-was varied such that M+ was either triphenylsulfoniuni (TPS+) or diphenyliodonium (DPfl), and X-was trif luoromethanesulfonate (TFA),-toluenesulfonate (TSA),-eamphorsulfonate(CSA-), and hexadecylsulfonate (HDSA).-The relative photospeed of these resists corresponded to the pKa of the photogenerated acid generated from the anion, TFA>TSA>HDSA>CSA. The TPSTSA-based resist showed the lowest diffusion coefficient, D = 2.7 x 10-5 ,uni2/s , as estimated from linewidth vs, postexposurebake(PEB) time plots. This paper also shows a unique advantage of onium salts in that they can show a maximum dissolution rate ratio, Rp/Rrnin, at less blocked polymer levels, where Rp is the dissolution rate of the blocked polymer, and R,77,1 is the dissolution rate of the unexposed blocked polyrner/5% onium salt. The dissolution rate ratio was 250 using a 10% blocked polymer, which approaches the inhibition capability of PAC/Novolak systems. This work on PAG structural variation has led to the development of XP-9402 positive DUV resist, which is linear to 0.225 um on a 0.53 NA excimer laser stepper at a photospeed of 46 inJ/cm2. This resist shows good postexposure delay stability for up to two hours, without the use of a covercoat. The second part of this paper discusses our work on negative DUV resists, where low molecular weight poly(p-vinyl)phenol (PVP) provides highest resolution performance in negative DUV resists. The PVP-based resists suffer from microbridging in 0.26 N TMAH developer. Finally, it is shown that with altered PVP, high resolution with negative DUV resists without niicrobridging in 0.26 N TMAH developer can be achieved.

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