Transport characterization and quantum dot coupling in commercial 22FDX

TL;DR

This paper systematically characterizes the transport properties and quantum dot coupling in the commercial 22FDX platform, providing insights for silicon spin qubit fabrication and optimization.

Contribution

It introduces a qubit pre-screening protocol and demonstrates quantum dot coupling along different channel directions in 22FDX, with analysis of process impacts and bias effects.

Findings

Effective mobility varies with process parameters and temperature.

Stable honeycomb charge stability diagrams indicate high-quality quantum dot coupling.

Forward body bias enhances qubit device performance and stability.

Abstract

Different groups worldwide have been working with the GlobalFoundries 22nm platform (22FDX) with the hopes of industrializing the fabrication of Si spin qubits. To guide this effort, we have performed a systematic study of six of the foundry's processes of reference (POR). Using effective mobility as a figure of merit, we study the impact of gate stack, channel type and back bias as a function of temperature. This screening process selected qubit devices that allowed us to couple quantum dots along both the length and width of the Si channel. We present stability diagrams with clear and regular honeycomb patterns, where spurious elements such as dopants are not observed. By combining these results with room and low temperature simulations, we provide insights into potential technology optimizations and show both the utility of qubit pre-screening protocols as well as the advantages of leveraging forward body bias within an FDSOI (Fully Depleted Silicon-On-Insulator) qubit platform.