An analysis of superconducting chip-to-chip interconnections.

The main problem in conventional interconnections is that the finite conductivity of metals limits the useful length of a signal transmission line. High temperature superconductors offer an alternative that may provide longer or denser interconnections. The critical current density in these materials limits the minimum wire dimensions, and determines the applications that can benefit from superconducting interconnections. At the present level of 10 sup 3 A/cm sup 2, superconducting lines are better than copper only for signal paths exceeding 1 meter, severely limiting the number of useful applications. At 10 sup 4 A/cm sup 2, a significant number of potential advantages exist, and at 5x10 sup 5 A/cm sup 2, superconducting interconnections could entirely replace metals in a high performance system. Reducing the signal levels used for semiconductor devices would shift these conclusions significantly toward widespread use of superconductors.