Capacitively-coupled quantum dots in commercial 22FDX® linear qubit arrays

Several groups worldwide have been working with the GlobalFoundries^TM industry-leading 22FDX® (22nm FDSOI) platform to design and demonstrate quantum dot (QD) feasibility and push FDSOI (Fully Depleted Silicon-On-Insulator) qubits to the next stage of commercialization. In this work we take a rigorous approach to studying 22FDX® and use effective carrier mobility as a figure of merit to screen six potential processes of reference from GlobalFoundries^TM. Having commissioned wafers with in-die process splits along with integrated test structures and qubit arrays, we study the effects of front-gate metal, front-gate equivalent oxide thickness, back bias, and temperature on the effective mobility of MOSFETs. With confirmation from both experiment and simulation, we identify the most promising qubit process split and leverage this information to couple QDs both along the length and width of the Si channel within linear (1xN) and bi-linear (2xN) arrays, respectively. For both array types, we present stability diagrams with clear honeycomb patterns that exhibit zero spurious elements such as those due to dopants or defects. Together, this systematic study provides insights into potential technology optimization, showing the necessity of pre-screening protocols as well as the advantages of leveraging forward back bias in a 22FDX® qubit platform.