  Superconductor-insulator-ferromagnet-superconductor (SIFS) Josephson tunnel
junctions based on Nb\Al2O3\Ni\Cu\Nb stacks with a thickness step in the
metallic NiCu interlayer were fabricated. The step height of a few 0.1 nm was
defined by optical lithography and controlled etching of both Nb and NiCu
layers. Experimentally determined junction parameters by current-voltage
characteristics and Fraunhofer pattern indicate a uniform NiCu thickness and
similar interface transparencies for etched and non-etched parts. The critical
current diffraction pattern was calculated and measured for stepped junctions
having the same ground phase difference but different critical current
densities in both halves. The measured data show a good agreement with
simulations.
