Investigation of charge storage and retention characteristics of silicon nitride in NVM based on InGaZnO channels for system-on-panel applications

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• 作者：Hong Hanh Nguyen ; Raja Jayapal ; Ngoc Son Dang ; Van Duy Nguyen ; Thanh Thuy Trinh ; Kyungsoo Jang ; Junsin Yi
• 关键词：Nonvolatile memory (NVM) ; Nitride/nitride/oxynitride (NNO) ; Plasma-assisted oxidation ; Amorphous InGaZnO (a-IGZO) ; Si-rich silicon nitride (Si-rich SiNx) ; Deep-trapping ; Shallow-trapping ; Low temperature ; Random-access storage
• 刊名：Microelectronic Engineering
• 出版年：2012
• 出版时间：October, 2012
• 年：2012
• 卷：98
• 期：Complete
• 页码：34-40
• 全文大小：1278 K

文摘

Si-rich silicon nitride (SiN_x) is a good charge storage material for the charge trap type of nonvolatile memory (NVM) because of its high density of charge traps. In this study, NVM devices were fabricated with nitride-nitride-oxynitride (NNO) stack structure using Si-rich SiN_x as the charge trapping layer and amorphous InGaZnO (a-IGZO) films as the active layer. The charge storage characteristics of Si-rich SiN_x were studied by controlling the gas flow ratio of SiH₄:NH₃ from 6:1 to 6:5. The characteristics were used to determine the optimal condition for the charge-trapping layer. The amorphous silicon clusters in the Si-rich SiN_x layer enhance the charge storage capacity of devices. High-k and high-density N-rich SiN_x films, which are used as a blocking layer, improve the vertical scaling and charge retention characteristics of NVM devices. NVM devices of the NNO structure with SiO_xN_y tunneling thickness of 2.5 nm and Si-rich SiN_x charge-trapping layer were investigated as the gas flow ratio of SiH₄:NH₃ was changed from 6:1 to 6:5. The NVM device with SiO_xN_y tunneling thickness of 2.5 nm at gas flow SiH₄:NH₃ ratio of 6:3 showed a large memory window of 3 V at a low operating voltage with a programming voltage of only +10 V in 1 ms. Moreover, the retention properties of the memory exceeded 94 % after 10 years. Therefore, the bottom-gate NNO NVM using a-IGZO active layer at low temperature has become a potential device for flexible substrate memory display systems.