Industrial quantum dot arrays for spin-qubit quantum computation by all-optical 300mm lithography
Anne-Marije Zwerver, Tobias Krähenmann, Stephanie Bojarski, Hubert George, Brennen Mueller, James Clarke, Lieven Vandersypen
On the road to building a quantum computer, spin qubits in gate-defined, silicon quantum dots stand out as promising qubit implementations. Advantages are their small size, long coherence times and compatibility with semiconductor technology. However, all quantum dot arrays fabricated to date rely on electron beam lithography for their fine gate patterns, even those processed on 300 mm process lines. Successfully integrating the many thousands of qubits that will be needed to solve real-world problems with a quantum computer, will require advanced semiconductor manufacturing, including all-optical lithography.
Here, we present the first quantum dot arrays made entirely with optical lithography in an industrial 300 mm processing line. We demonstrate well-controlled single and double quantum dots formed in an isotopically enriched 28Si-MOS substrate. In the many-electron regime independent tunnel-barrier control is shown, a prerequisite for high-fidelity two-qubit control. Using state of the art charge detection methods, we are able to observe single-electron occupation of these quantum dot arrays. The few-electron regime shows stable device behavior, with dots forming both under the plunger and barrier gates, where we analyze the occurrence of spurious dots.
Data-driven process improvements of the quantum dots have led to a significant increase in charge-sensing sensitivity, capable of single shot read-out.