200nm-pitched, Superconducting Nb Interconnects for Cryo-CMOS Application

A 200nm-pitched, superconducting niobium (Nb) interconnects with TiN protecting layer are fabricated on a 300-mm wafer for cryo-CMOS used in Quantum State Controller (QSC) application. The developed Nb interconnects show superior superconductivity with a Tc of 7.8 K and a record-high Jc of 64MA/cm² at 4.2 K, which is high enough to local interconnects used in a cryo-CMOS circuit. For the first time, the SPICE simulation, using a 65nm-node cryogenic (4K) PDK with a technology file including Nb superconducting interconnects, estimates 40% improvement in signal delay in a typical use case. This result indicates that the power consumption in cryogenic CMOS operation can be reduced by the superconducting interconnects, as the operating voltage can be lowered while maintaining the same operational speed as that with the Cu interconnects.