Dynamic-Gate-Stress-Induced Degradation in Bridged-Grain Polycrystalline Silicon Thin-Film Transistors
Dynamic-Gate-Stress-Induced Degradation in Bridged-Grain Polycrystalline Silicon Thin-Film Transistors
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DOI：
10.1109/ted.2016.2601218
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发表时间：
2016-08
影响因子：
3.1
通讯作者：
Meng Zhang;Zhihe Xia;Wei Zhou;Rongsheng Chen;M. Wong;H. Kwok
中科院分区：
文献类型：
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作者：
Meng Zhang;Zhihe Xia;Wei Zhou;Rongsheng Chen;M. Wong;H. Kwok
本文系统地研究了桥晶多晶硅薄膜晶体管的退化行为。器件的退化表现出两个阶段的行为，这是相关的脉冲下降时间（tf）。更快的tf在第一级中带来更大的导通电流（ION）增加，并且在第二级中带来更大的ION减小。发现电子俘获/注入栅氧化层和动态热载流子效应分别是导致第一阶段离子增加和第二阶段离子减少的原因。与普通多晶硅薄膜晶体管相比，在相同的动态栅应力下，BG多晶硅薄膜晶体管显示出更可靠的性能。在第一阶段中BG多晶硅TFT中较大的ION增加归因于栅极氧化物附近的沟道中增强的垂直电保持，而在第二阶段中小得多的ION减少归因于由有源沟道内的多个反向偏置结之间的保持的共享引起的横向电保持减少。结合瞬态仿真，阐明了第一阶段和第二阶段的退化机制。此外，还阐明了第一阶段降解对第二阶段降解的影响。
In this paper, degradation behaviors of bridged-grain (BG) polycrystalline silicon (poly-Si) thin-hlm transistors (TFTs) are systematically characterized and investigated. Device degradation exhibits a two-stage behavior, which is related to pulse falling time (tf). A faster tf brings a larger ON-current (ION) increase in the first stage and a larger ION decrease in the second stage. Electron trapping/injection into gate oxide and dynamic hot carrier effect are found to be responsible to ION increase in the hrst stage and ION decrease in the second stage, respectively. Compared with normal poly-Si TFTs, BG poly-Si TFTs show much more reliable performance under the same dynamic gate stress. The larger ION increase in the hrst stage in BG poly-Si TFTs is attributed to the enhanced vertical electric held in the channel near the gate oxide, while the much smaller ION decrease in the second stage is attributed to lateral electric held reduction caused by the sharing of the held across multiple reversely biased junctions inside the active channel. Incorporated with transient simulations, the degradation mechanisms for both the first stage and the second stage are elucidated. In addition, the impact of the hrst-stage degradation on the second-stage degradation is also clarified.