Title :
Effect of photomask pattern shape for a junction counter-electrode on critical current uniformity and controllability in Nb/AlOx/Nb junctions
Author :
Akaike, H. ; Kitagawa, Y. ; Satoh, T. ; Hinode, K. ; Nagasawa, S. ; Hidaka, M.
Author_Institution :
Supercond. Res. Lab., ISTEC, Ibaraki, Japan
fDate :
6/1/2005 12:00:00 AM
Abstract :
The authors evaluated the effect of photomask pattern shape for a counter-electrode on critical current Ic uniformity and controllability in Nb/AlOx/Nb junctions. Circular, square, and 2 kinds of optical proximity correction (OPC) square patterns were used as the mask pattern shape. Although there was no difference in the Ic uniformity between square and OPC junctions, the OPC junctions exhibited smaller shrinkage in junction size than the square junction. In addition, the OPC junctions improved the chip-to-chip variation in the shrinkage. The circular junction exhibited the smallest variation in the shrinkage, and had an advantage in Ic uniformity for smaller than 1.0 μm2 junctions in comparison with the other junctions. The shrinkage of the circular junction was the largest of all the junctions. This paper describes the recommended choice of the photomask pattern shape for several Nb LSI technologies.
Keywords :
aluminium compounds; controllability; critical currents; large scale integration; masks; niobium; proximity effect (lithography); superconducting junction devices; LSI technology; Nb-AlOx-Nb; chip-to-chip variation; circular junction; controllability; critical current uniformity; junction counter electrode; optical proximity correction; photomask pattern shape; Bars; Controllability; Critical current; Etching; Laboratories; Large scale integration; Lithography; Niobium; Optical scattering; Shape control; Circular junction; Nb/AlOx/Nb; optical proximity correction junction; photomask pattern shape;
Journal_Title :
Applied Superconductivity, IEEE Transactions on
DOI :
10.1109/TASC.2005.849704
