Next-generation ferroelectric memories based on FE-HfO2

In recent years, and with the discovery of ferroelectricity in hafnium oxide, it was possible to scale down ferroelectric memory cells in both transistor and capacitor configurations. This study reports the latest advances for FE-HfO₂-based memory cells and arrays. For the 1T FeFET memory approach, retention in the range of 10 μs up to 10⁴ seconds was measured both after 10² and 10⁴ endurance cycles. At room temperature, memory windows of 0.8 V and 0.7 V were extrapolated to ten years respectively. Moreover, a novel operating scheme for a 1T FeFET AND architecture is presented allowing for true random access operation of the array. With respect to capacitor-based memory cells, high aspect ratio ferroelectric trench capacitors are demonstrated which show proper memory characteristics up to 10⁵ cells in parallel. In order to bring these concepts closer to commercialization, device statistics of larger amounts of memory cells have to be provided. For the first time, the functionality of small FeFET memory arrays is shown and the statistical distribution of memory characteristics is analyzed. We provide evidence that with the proper choice of material composition, device size and operating conditions, the realization of memory products utilizing HfO₂-based FeFET arrays seems viable in the future.