First demonstration of 2T0C-FeDRAM: a-ITZO FET and double gate a-ITZO/a-IGZO FeFET with a record-long multibit retention time of >4-bit and >2000 s

• Published in: Nanoscale 2024-09, Vol.16 (35), p.16467-16476
• Main Authors: Noh, Tae Hyeon, Chen, Simin, Kim, Hyo-Bae, Jin, Taewon, Park, Seoung Min, An, Seong Ui, Sun, Xinkai, Kim, Jaekyun, Han, Jae-Hoon, Ahn, Ji-Hoon, Ahn, Dae-Hwan, Kim, Younghyun
• Format: Article
• Language: English
• Subjects: Artificial intelligence; Data storage; Dynamic random access memory; Ferroelectricity; Field effect transistors; Heterostructures; Indium gallium zinc oxide; Memory management; Retention; Semiconductor devices; Transistors; Zirconium oxides
• ISSN: 2040-3364; 2040-3372; 2040-3372
• DOI: 10.1039/d4nr02393e

Conventional DRAM, consisting of one transistor and one capacitor (1T1C), requires periodic data refresh processes due to its limited retention time and data-destructive read operation. Here, we propose and demonstrate a novel 3D-DRAM memory scheme available with a single transistor and a single ferroelectric field-effect transistor (FeFET) DRAM (2T0C-FeDRAM), which offers extended retention time and non-destructive read operation. This architecture uses a back-end-of-line (BEOL)-compatible amorphous oxide semiconductor (AOS) that is suitable for increasing DRAM cell density. Notably, the device structures of a double gate a-ITZO/a-IGZO FeFET, used for data storage and reading, are engineered to achieve an enlarged memory window (MW) of 1.5 V and a prolonged retention time of 10 4 s. This is accomplished by a double gate and an a-ITZO/a-IGZO heterostructure channel to enable efficient polarization control in hafnium-zirconium oxide (HZO) layers. We present successful program/erase operations of the double gate a-ITZO/a-IGZO FeFET through incremental step pulse programming (ISPP), demonstrating multi-level states with remarkable retention characteristics. Most importantly, we perform 2T0C-FeDRAM operations by electrically connecting the double gate a-ITZO/a-IGZO FeFET and the a-ITZO FET. Leveraging the impressive performance of the double gate a-ITZO/a-IGZO FeFET technology, we have effectively showcased an exceptionally record-long retention time exceeding 2000 s and 4-bit multi-level states, positioning it as a robust contender among emerging memory solutions in the era of artificial intelligence. We successfully demonstrated a 2T0C-FeDRAM with a record-long multibit retention time exceeding 2000 seconds and 4-bit (19 states) capability, attributed to a V SN of 0 V leveraging the non-volatile properties of ferroelectrics.