Browse Prior Art Database

High-Uniformity Josephson Edge Junctions

IP.com Disclosure Number: IPCOM000042188D
Original Publication Date: 1984-May-01
Included in the Prior Art Database: 2005-Feb-03
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Brosious, PR: AUTHOR

Abstract

Controlling the wafer plane with respect to the cathode plane (the Z parameter) increases the uniformity of niobium edge junctions and planar junctions in Josephson junction technology. Fig. 1 shows a general RF plasma system for processing high uniformity Nb edge Josephson junctions. It has been known for some time that rotation about both the cathode and wafer axes was capable of averaging out the cathode radial systematics in the plasma. This accounts for reduction of J (current density of junctions) systematics of nearly 20%/ chip to near zero arising from the cathode radial. It was further found that a magnetic field, as shown in Fig. 1, could average out residual wafer conical distributions on the order of 15%/chip to near zero, but this was the limit.

This text was extracted from a PDF file.
This is the abbreviated version, containing approximately 56% of the total text.

Page 1 of 1

High-Uniformity Josephson Edge Junctions

Controlling the wafer plane with respect to the cathode plane (the Z parameter) increases the uniformity of niobium edge junctions and planar junctions in Josephson junction technology. Fig. 1 shows a general RF plasma system for processing high uniformity Nb edge Josephson junctions. It has been known for some time that rotation about both the cathode and wafer axes was capable of averaging out the cathode radial systematics in the plasma. This accounts for reduction of J (current density of junctions) systematics of nearly 20%/ chip to near zero arising from the cathode radial. It was further found that a magnetic field, as shown in Fig. 1, could average out residual wafer conical distributions on the order of 15%/chip to near zero, but this was the limit. The Z parameter is a much stronger first order effect with wafer axis symmetry (namely, the position Z of the wafer plane with respect to the cathode plane) that must be dealt with first before the above second order parameters (rotation and magnetic field) are optimized. In practice, as shown in Fig. 2, it is easy to determine the optimum Z parameter for each wafer by carrying out a plasma oxidation for three Z positions: recessed; on plane; and raised above plane. One then calculates the systematic spreads for the edge junction orientation effect as a function of the Z parameter, and likewise for the mean J on wafer and for the radial systematics of planar Nb junctio...