Self-contained measurement of thin-film superconducting penetration depths and nonsuperconducting film thicknesses in Josephson integrated circuits

In measurements of superconducting thin-film penetration depths, the need for a reference penetration depth has been eliminated by a modification of the direct-coupled SQUID technique. Furthermore, the technique is convenient for accurate measurements of insulator and thin-film resistor thicknesses in superconducting integrated circuits. Measurements of the penetration depths and insulator thicknesses have been obtained on different chips from a few wafers of a single fabrication run. The results indicate for the first time, on a small scale, the degree of chip-to-chip and wafer-to-wafer control presently obtainable for these parameters.