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 . #
We evaluated the fabrication of hole pattems in 157 nm lithography. In order to fabricate fine hole patterns to be required devices below 65 nm technology node, we have enhanced resolution and achieved a 65 nm hole pattem by using a high numerical aperture (=OM) stepper, a phase shifting mask, highly transparent resist materials, and a shrink process.
We studied the effects of polarization control that is expected to minimize image degradation caused by the polarization effect for various patterns. The resolution of line-and-space (L&S) patterns was most enhanced by dipole illumination under polarization control. However, the polarization control did not improve resolution in dense contacts, although this was improved by normal quadrupole illumination. Consequently, it will be difficult to achieve the same resolution in dense contacts as in L&S patterns, even when advanced illumination and polarization control are applied. The resolution gap between L&S and dense contacts may reach up to a 40 nm pitch in the 45 nm node, particularly for immersion lithography using a hyper numerical aperture. We also found that 157 nm dry/immersion lithography has an advantage over 193 nm immersion lithography from the viewpoint of resolution gaps, on the basis of the assumption that both technologies would achieve the same resolution in L&S patterns.
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