True Nonvolatile High‐Speed DRAM Cells Using Tailored Ultrathin IGZO

• DOI: 10.1002/adma.202210554
• Publication Date: 2023-03-09T17:24:22Z
• Authors: Qianlan Hu; Chengru Gu; Qijun Li; Shenwu Zhu; Shiyuan Liu; Yu Li; Lining Zhang; Ru Huang; Yanqing Wu
• Keywords: Dram; Non-Volatile Memory; Ohmic contact

Severe power consumption in the continuous scaling of Silicon-based dynamic random access memory (DRAM) technology quests for a transistor with much lower off-state leakage current. Wide bandgap amorphous oxide semiconductors, especially indium-gallium-zinc-oxide (IGZO) exhibit many orders magnitude leakage. However, they are typically heavily n-doped and require negative gate voltage to turn off, which prevents them from true nonvolatile operation. The efforts on doping density reduction result mobility degradation high Schottky barriers at contacts, causing severe on-current operation speed DRAM cells. Here, high-speed cells successfully demonstrated by deep suppression IGZO channel using situ oxygen ion beam treatment ohmic contact engineering inserting thin In-rich indium-tin-oxide (ITO) regions. A record 40 µA µm-1 large positive threshold 1.78 V enables first fastest write 10 ns data retention up 25 h under interruption, five higher than previously projected values.