  Fluxonium qubits are recognized for their high coherence times and high
operation fidelities, attributed to their unique design incorporating over 100
Josephson junctions per superconducting loop. However, this complexity poses
significant fabrication challenges, particularly in achieving high yield and
junction uniformity with traditional methods. Here, we introduce an overlap
process for Josephson junction fabrication that achieves nearly 100% yield and
maintains uniformity across a 2-inch wafer with less than 5% variation for the
phase slip junction and less than 2% for the junction array. Our compact
junction array design facilitates fluxonium qubits with energy relaxation times
exceeding 1 millisecond at the flux frustration point, demonstrating
consistency with state-of-the-art dielectric loss tangents and flux noise
across multiple devices. This work suggests the scalability of high coherence
fluxonium processors using CMOS-compatible processes, marking a significant
step towards practical quantum computing.
