Uniform Spin Qubit Devices with Tunable Coupling in an All-Silicon 300 mm Integrated Process

Larger arrays of electron spin qubits require radical improvements in fabrication and device uniformity. Here we demonstrate excellent qubit device uniformity and tunability from 300K down to mK temperatures. This is achieved, for the first time, by integrating an overlapping polycrystalline silicon-based gate stack in an ‘all-Silicon’ and lithographically flexible 300mm flow. Low-disorder Si/SiO2 is proved by a 10K Hall mobility of 1.5·10⁴ cm²/Vs. Well-controlled sensors with low charge noise (3.6 µeV/√Hz at 1 Hz) are used for charge sensing down to the last electron. We demonstrate excellent and reproducible interdot coupling control over nearly 2 decades (2-100 GHz). We show spin manipulation and single-shot spin readout, extracting a valley splitting energy of around 150 µeV. These low-disorder, uniform qubit devices and 300mm fab integration pave the way for fast scale-up to large quantum processors.