Development of highly integrated RSFQ circuits on the basis of intrinsically shunted Josephson junctions

At PTB, for application in rapid single flux quantum (RSFQ) and voltage sta ndard circuits, the development of highly integrated SDE circuits is focuse d on devices based on intrinsically shunted Josephson junctions in the SINI S and SNS technologies. In SINIS technology, the fabrication process has be en optimized to values of the critical current density of j(C) = 500 A/cm(2 ) and the characteristic voltage of V-C = 190 muV. To raise the circuit int egration level, successive steps of development are shown by the example of the layout of an elementary RSFQ cell designed for higher values of jc. In SNS technology, a fabrication process has been developed to produce-small ramp-type junctions with contact areas smaller than 0.4 mum(2) and with val ues for j(C) and V-C of about j(C) = 200 kA/cm(2) and V-C = 20 muV The desi gn allows the SNS junction size to be further reduced down to the deep sub- micron range. (C) 2001 Elsevier Science B.V. All rights reserved.