Superconducting devices at 300mm wafer scale
Niobium has a superconducting transition temperature of ~ 9 K, and is hence a good choice for superconducting logic circuits that can operate at liquid helium temperatures. Single flux quantum (SFQ) circuits have been utilized for high speed RF circuits, and recently have been proposed for control and readout of superconducting quantum computing hardware. NY CREATES and its partners are working at the 300mm fab to enable the fabrication of Nb-based interconnects, Josephson junctions and high kinetic inductance elements that utilize NbN nanowire structures. Cryogenic characterization is conducted with the help of the Hamilton group at Auburn University. We are also collaborating with Prof. Majumdar (Indian Institute of Science, Bengaluru) on superconducting nanowire single photon detectors fabricated using 300mm-wafer scale process technologies.
Hunter Frost is working on his Ph.D thesis at SUNY Polytechnic Institute, characterizing the materials, interfaces and processes critical to Nb/TaN/Nb junctions fabricated at 300mm wafer scale, and studying such junctions for their application to qubits. He is co-advised by Chris Borst, and Papa Rao. Hunter obtained his B.S in Nanoengineering from SUNY Polytechnic Institute in 2020 and immediately afterwards started working towards his doctorate. Hunter’s graduate school work is supported by TEL Technology Center America, where Hunter is also an employee working on advanced CMOS process tool development.
Aluminum, in contrast, has a superconducting transition temperature of ~ 1 K, and has been the material of choice for superconducting qubits due to the ease with which a tunnel barrier of aluminum oxide can be formed at room temperature with tight thickness control. The NY CREATES team has been working to characterize the processes and the integration required for all-300mm fabrication of Al-based Josephson junctions and qubits – verifying CMP characteristics, surface defectivity, and interface engineering among others.