Fabrication of all YBaCuO trilayer Josephson junctions with YBaCuO wiring layer

We report a fabrication process of c-axis oriented all YBaCuO trilayer Josephson junctions with YBaCuO wiring layers. The trilayer junctions consisted of YBaCuO (170nm)/PrBaCuO (28 nm)/YBaCuO (170 nm) structures. CeO₂ films (520nm) and YBaCuO films (1.2 μm) were used as insulating layers and wiring layers, respectively. A junction with a dimension of 7 μm×7 μm showed a critical current I_c of 1.6 mA and a junction resistance R_n of 1.2 Ω at 4.2 K. The values of the critical current density and the I_cR_n product were estimated to be 3.3kA/cm² and 1.9 mV, respectively. Note that the junction exhibited I_cR_n product of 1.0 mV even at 30 K. From these results, the junction is promising candidate for satisfying the requirements for HTS integrated circuits.