Fabrication of uniform Manhattan-style transmon qubits on 150 mm wafers

To scale up the number of qubits patterned onto a single wafer, the quantum processor rapidly increases in its footprint. To maintain the processor’s performance, a precise control over the frequencies of individual qubits is often of great importance. Highly coherent transmon qubits can be fabricated through angled depositions. The qubit frequency is directly associated with room temperature Josephson junction (JJ) resistance via Ambegaokar–Baratoff relation. When fabricating on large-scale wafer, since the evaporation source is point-like, the effective deposition angles are different for individual JJs depending on their positions on the wafer. It inevitably leads to varying JJ resistances even for the same designed JJ size. Consequently, it presents a challenging task to accurately allocate design qubit frequencies on a large-scale wafer. In this work, we fabricate identical Manhattan-style JJs across a 150 mm wafer to examine the spatial uniformity of their resistances. To compensate the variation of the deposition angle, the designed JJ sizes are individually adjusted according to their positions on the wafer. The room temperature resistance measurements show a variation in the resistance of about 10% across the wafer. The uniformity is further improved by local annealing of individual JJs post fabrication. The resultant standard deviation of the resistance is reduced to less than 1% of the average JJ resistance, which is suitable for large scale qubit production.