Impacts of HfO2/ZnO Stack-Structured Charge-Trap Layers Controlled by Atomic Layer Deposition on Nonvolatile Memory Characteristics of In-Ga-Zn-O Channel Charge-Trap Memory Thin-Film Transistors

IEEE Journal of the Electron Devices Society

Sung-Min Yoon¹  So-Yeong Na¹ 

[1] Department of Advanced Materials Engineering for Information and Electronics, Kyung Hee University, Yongin, South Korea;

关键词: High-k material;    HfO₂;    ZnO;    ALD;    IGZO charge-trap memory;   

DOI  :  10.1109/JEDS.2019.2908255

来源: DOAJ

【 摘 要 】

We fabricated the charge-trap memory thin film transistors (CTM-TFTs) using InGaZnO (IGZO) active channel and HfO₂/ZnO stack-structured charge-trap layer (CTL). To investigate the effects of the number and thickness of HfO₂ layers inserted between the ZnO within the stack structured CTLs on the device characteristics, 2-nm-thick HfO₂ thin films were inlaid once, twice, and four times, and 4-nm-thick HfO₂ layers were introduced twice between the ZnO layers. The CTM-TFTs using the stack structured CTLs with 4-nm-thick HfO₂ layers showed good memory characteristics, including large memory window (MW) of 25 V and rapid program/erase (P/E) speed of 500 μs because of high total trap density of HfO₂ with a sufficient thickness to provide charge-trap centers. On the contrary, relatively narrow MW of 16 V and slower P/E speed of 100 ms were obtained for memory device using the stacked CTL with four HfO₂ layers of 2 nm. The HfO₂ layer with a thickness as thin as 2 nm was supposed to act as just dielectric films deactivating the trapping or migration of electron charges due to too thin film thickness. The gate-stack structures confirmed from STEM images suggested that the modulations in memory device characteristics with different CTL structures resulted from the variations in designs of stack structured CTLs when the interface qualities within the gate-stacks were well prepared. Moreover, the detailed fabrication conditions were found to be important control parameters to reproducibly obtain reliable memory device characteristics.

【 授权许可】

Unknown