Hidden mechanisms in next-generation AI memory device

Professor Seyoung Kim and Dr. Hyunjeong Kwak from the Departments of Materials Science & Engineering and Semiconductor Engineering at POSTECH, in collaboration with Dr. Oki Gunawan from the IBM T.J. Watson Research Center, have become the first to uncover the hidden operating mechanisms of Electrochemical Random-Access Memory (ECRAM), a promising next-generation technology for AI. This groundbreaking study has been published in the journal, Nature Communications.

As AI technologies advance, data processing demands have exponentially increased. Current computing systems, however, separate data storage (‘memory’) from data processing (‘processors’), resulting in significant time and energy consumption due to data transfers between these units. To address this issue, researchers developed the concept of ‘In-Memory Computing.’

‘In-Memory Computing’ enables calculations directly within memory, eliminating data movement and achieving faster, more efficient operations. ECRAM is a critical technology for implementing this concept. ECRAM devices store and process information using ionic movements, allowing for continuous analog-type data storage. However, understanding their complex structure and high-resistive oxide materials has remained challenging, significantly hindering commercialization.

To address this, the research team developed a multi-terminal structured ECRAM device using tungsten oxide and applied the ‘Parallel Dipole Line Hall System’, enabling observation of internal electron dynamics from ultra-low temperatures (-223°C, 50K) to room temperature (300K). They observed, for the first time, that oxygen vacancies inside the ECRAM create shallow donor states (~0.1 eV), effectively forming ‘shortcuts’ through which electrons move freely. Rather than simply increasing electron quantity, the ECRAM inherently creates an environment facilitating easier electron transport. Crucially, this mechanism remained stable even at extremely low temperatures, demonstrating the robustness and durability of the ECRAM device..

Prof. Seyoung Kim from POSTECH emphasized, “This research is significant as it experimentally clarified the switching mechanism of ECRAM across various temperatures. Commercializing this technology could lead to faster AI performance and extended battery life in devices such as smartphones, tablets, and laptops.”

This work was supported by K-CHIPS(Korea Collaborative & High-tech Initiative for Prospective Semiconductor Research)funded by the Ministry of Trade, Industry & Energy of Korea (MOTIE).

Notes:

1. ECRAM(Electrochemical Random-Access Memory): An electrochemical memory device whose channel conductivity varies according to the concentration of ions within the channel. This behavior allows for the expression of analog memory states. The device features a three-terminal structure consisting of a source, drain, and gate. By applying voltage to the gate, ion movement is controlled, and the channel conductivity is read through the source and drain.

2. Parallel Dipole Line Hall System, PDL Hall System: A Hall measurement system composed of two cylindrical dipole magnets. When one magnet is rotated, the other rotates automatically, enabling the generation of a strong, superimposed magnetic field. This configuration allows for enhanced sensitivity in observing internal electron behaviors.