Industrially fabricated single-electron quantum dots in Si/Si-Ge heterostructures

TL;DR

This study demonstrates that industrial CMOS fabrication processes can produce high-quality Si/Si-Ge quantum dot spin qubits suitable for scalable quantum computing, maintaining key device characteristics and coherence properties.

Contribution

It shows that industrial CMOS-compatible fabrication can reliably produce high-performance Si/Si-Ge quantum dots for quantum computing applications.

Findings

Quantum dots exhibit state-of-the-art charge sensing and noise characteristics.

Fabrication process preserves heterostructure quality and qubit coherence.

Scalable device layout compatible with existing CMOS technology.

Abstract

This paper reports the compatibility of heterostructure-based spin qubit devices with industrial CMOS technology. It features Si/Si-Ge quantum dot devices fabricated using Infineon's 200 mm production line within a restricted thermal budget. The devices exhibit state-of-the-art charge sensing, charge noise and valley splitting characteristics, showing that industrial fabrication is not harming the heterostructure quality. These measured parameters are all correlated to spin qubit coherence and qubit gate fidelity. We describe the single electron device layout, design and its fabrication process using electron beam lithography. The incorporated standard 90 nm back-end of line flow for gate-layer independent contacting and wiring can be scaled up to multiple wiring layers for scalable quantum computing architectures. In addition, we present millikelvin characterization results. Our work exemplifies the potential of industrial fabrication methods to harness the inherent CMOS-compatibility of the Si/Si-Ge material system, despite being restricted to a reduced thermal budget. It paves the way for advanced quantum processor architectures with high yield and device quality.