Title :
An improved etching process used for the fabrication of submicron Nb/AlO/sub x//Nb Josephson junctions
Author :
Aoyagi, M. ; Maezawa, M. ; Nakagawa, H. ; Kurosawa, I. ; Takada, S.
Author_Institution :
Electrotech. Lab., Ibaraki, Japan
fDate :
6/1/1995 12:00:00 AM
Abstract :
It is important to develop a reliable and reproducible fabrication process of submicron Nb/AlO/sub x//Nb Josephson junctions to improve the integration level and the operating speed of the Josephson LSI circuit. For this purpose, we have developed an improved etching process by introducing a dummy etching process and using a scanning electron microscope (SEM) as an etching end-point detector. The dummy etching process improves the anisotropy of a reactive ion etching (RIE) process using CF/sub 4/. The etching residue around a junction is detected easily and correctly by the SEM observation. We have successfully fabricated Nb/AlO/sub x//Nb Josephson junctions with critical current density of 10/sup 4/ A/cm/sup 2/ using the cross-line patterning (CLIP) method and electron beam lithography, where the junction size was varied from 2 /spl mu/m to 0.5 /spl mu/m at 0.1 /spl mu/m intervals. High-quality submicron junctions for integrated circuits with suitable critical current variations were obtained.<>
Keywords :
Josephson effect; aluminium compounds; critical current density (superconductivity); electron beam lithography; electron microscopy; integrated circuit technology; large scale integration; niobium; scanning electron microscopy; sputter etching; superconducting device testing; superconducting integrated circuits; superconductor-insulator-superconductor devices; 0.5 to 2 micron; CF/sub 4/ etchant; Josephson LSI circuit; Nb-AlO-Nb; Nb/AlO/sub x//Nb Josephson junctions; RIE process; SEM etching end-point detector; SEM observation; anisotropy improvement; critical current density; cross-line patterning method; dummy etching process; electron beam lithography; etching process; integrated circuit fabrication; reactive ion etching; reproducible fabrication process; scanning electron microscope; submicron junction fabrication; Anisotropic magnetoresistance; Critical current density; Detectors; Etching; Fabrication; Integrated circuit reliability; Josephson junctions; Large scale integration; Niobium; Scanning electron microscopy;
Journal_Title :
Applied Superconductivity, IEEE Transactions on
