Can RSFQ logic circuits be scaled to deep submicron junctions?

Scaling of niobium RSFQ integrated circuit technology to deep submicron dimensions (linewidths of 300 nm or less) should permit increased clock rate (up to 250 GHz) and increased areal density of Josephson junctions (up to 1 million junctions/cm/sup 2/), without the need for external shunt resistors. It is shown how existing circuit layouts can be scaled down to these dimensions, while maintaining the precise timing essential for correct operation. Additional issues related to the practical realization of such circuits are discussed, including effects of self-heating and models for the generation and propagation of sub-ps single-flux-quantum pulses.