Development toward high-speed integrated circuits and AQUID qubits with Nb/AlO/sub x//Nb josephson junctions

Abstract

Our Nb/AlO/sub x//Nb planarized process has been upgraded by adding extra dielectric and Nb wiring layers and the installation of an Inductively Coupled Plasma (ICP) etcher. Much higher quartz etch rates as well as reduced residue are achieved with ICP etch. Etch uniformities of both Nb and quartz are also improved significantly. Damage to Nb during the fabrication process has been investigated. We have found that dry etching in SF/sub 6/ plasma has a significant effect on the quality of Nb films under certain conditions with damage coinciding with the presence of in situ deposited Al.