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The most commonly used physical realization of superconducting qubits forquantum circuits is a transmon. There are a number of superconducting quantumcircuits applications, where Josephson junction critical currentreproducibility over a chip is crucial. Here, we report on a robust chip scale$Al/AlO_x/Al$ junctions fabrication method due to comprehensive study of shadowevaporation and oxidation steps. We experimentally demonstrate the evidence ofoptimal Josephson junction electrodes thickness, deposition rate and depositionangle, which ensure minimal electrode surface and line edge roughness. Theinfluence of oxidation method, pressure and time on critical currentreproducibility is determined. With the proposed method we demonstrate$Al/AlO_x/Al$ junction fabrication with the critical current variation($\sigma/I_c$) less than 3.9% (from $150\times200$ to $150\times600$ $nm^2$area) and 7.7% (for $100\times100$ $nm^2$ area) over $20\times20$ $mm^2$ chip.Finally, we fabricate separately three $5\times10$ $mm^2$ chips with 18transmon qubits (near 4.3 GHz frequency) showing less than 1.9% frequencyvariation between qubit on different chips. The proposed approach andoptimization criteria can be utilized for a robust wafer-scale superconductingqubit circuits fabrication.

Improving Josephson junction reproducibility for superconducting quantum circuits: shadow evaporation and oxidation