We demonstrated the precise measurement of a 20-V programmable Josephson voltage standard (PJVS) system with an accuracy of 10 À9 . A 20-V PJVS chip including 524288 NbN/TiN x /NbN Josephson junctions (JJs) was used and operated in a cryocooler. By optimizing a microwave frequency, the widest current margin of a voltage step greater than 1 mA was obtained at 15.85 GHz. The maximum voltage of 17 V was also obtained at 18.00 GHz although we could not obtain voltages exceeding 20 V due to defective JJs. We also successfully compared the PJVS system with a 10-V Zener diode with an accuracy of 10 À8 . #
Tetrafluoroethylene-based copolymers with functionalized norbornenes were synthesized using a hydrocarbon and hydrofluorocarbon initiators and their fundamental properties, such as transparency at 157 nm and solubility in a standard alkaline developer were characterized. A high transparency, i.e., absorbance of less than 0.5 m Ϫ1 , and the increase of the dissolution rate in the standard alkaline developer were achieved. Positive-working resists formulated by the fluororesins were developed and showed fine patterns of 60 nm dense lines and spaces delineated by the exposure at 157 nm wavelength.
We describe and evaluate three kinds of pattern transfer processes that are suitable for 157-nm lithography. These transfer processes are 1) a hard mask (HM) process using SiO as a HM material, 2) a HM process using an organic bottom anti-reflecting coating (BARC)/SiN structure, and 3) a bi-layer process using a silicon-containing resist and an organic film as the bottom layer. In all of these processes, the underlayer of the resist acts as an anti-reflecting layer. For the HM processes, we patterned a newly developed fluorine-containing resist using a 157-nm microstepper, and transferred the resist patterns to the hard mask by reactive ion etching (RIE) with minimal critical dimension shift. Using the HM pattern, we then fabricated a 65nm WSi/poly-Si gate pattern using a high-NA microstepper (NA=O.85). With the bi-layer process, we transferred a 6Onm 1 : 1 lines and spaces pattern of a newly developed silicon-containing resist to a 300nm-thick organic film by RIE. The fabrication of a 65nm 1 : 1 gate pattern and 6Onm 1 : 1 organic film pattern clearly demonstrated that 157-nm lithography is the best candidate for fabricating sub-7Onm node devices.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.