Technology Topics

We have successfully demonstrated the preparation of ferromagnetic Co thin layers showing the current-induced domain wall motion (CIDWM), by using atomic layer deposition technique which is widely utilized in the three-dimensional LSI technologies. CIDWM is the key physical phenomenon for race-track memory^[1]. This result was presented in the international conference, IEEE INTERMAG 2023^[2].

HfO₂-based FeFET is a promising candidate for next-generation memory. The coupling between polarization reversal and charge trapping was revealed in this study. We demonstrated a novel operation scheme that strongly suppresses unintended programing of FeFET during memory array operation. These results were presented at the international conference IRPS 2023.

Ferroelectric MOS transistors using HfO₂ as the dielectric and Si as the current path have been widely researched and developed for memory applications including AI applications. Kioxia has fabricated a prototype ferroelectric Field Effect Transistor (FET) using TiO₂ as the current path and demonstrated high-speed, low-voltage operation and high cycle endurance. This achievement received the Best Contributed Paper Award at the international conference EDTM2023.

Selector devices are key components for next-generation high-density memory cell arrays. In this work, the reliability of selector devices has been studied in collaboration with imec, the world-leading R&D center in electronics technologies. The mechanism of the cycling-dependent threshold voltage instability has been clarified by combining electrical characterization and modeling techniques. These results were presented at the international conference IEDM2022.

HfO₂-FeFETs is a strong candidate for next-generation memory. In HfO₂-FeFETs memory the difference between "0" and "1" decreases after repeated write and erase operations. This cycle degradation, which remained largely unknown, has been clarified by high-speed charge center analysis. This achievement is expected to advance the practical application of HfO₂-FeFET memory. These results were presented at the international conference IEDM2021.

Recently, ferroelectric memories using ferroelectric-HfO₂ film have attracted much attention towards low-power and high-density in-memory computing for AI (artificial intelligence).

The challenge for achieving terabit-scale cross-point memory is to reduce operation current of a memory cell.
As a solution, we focused on a new non-volatile memory; Ag ionic memory.

We propose new memory cell technologies to realize even higher bit density file memories, as well as various high-speed nonvolatile memories.