搭桥晶粒多晶硅薄膜晶体管栅交流电应力下的退化行为与退化机制研究

摘要

本文主要研究了搭桥晶粒(BG)多晶硅薄膜晶体管(TFT)在栅交流电应力下的退化行为和退化机制.在栅交流应力下,动态热载流子效应主导了器件的退化.器件退化只与栅脉冲下降沿有关.越快的下降沿带来越大的动态热载流子退化.比起普通多晶硅TFT,BG多晶硅TFT的热载流子退化大幅度减弱.通过选择性的掺杂注入BG线,沟道中形成的PN结在反向偏置时可以有效分担栅交流电应力带来的电压差,从而减弱动态热载子退化.辅以瞬态模拟结果,栅交流电应力下的退化机制被阐明.所有的测试结果都表明这种高性能高可靠性的BG多晶硅TFT在片上系统应用中具有很大的应用前景.%Degradation behavior and degradation mechanism of bridged-grain (BG) polycrystalline silicon thin film transistors (TFTs) under AC gate bias stress are studied and investigated.It is found that dynamic hot carrier (HC) effect dominates the device degradation.The degradation is only related to gate pulse falling time (tf).Faster tf brings larger dynamic HC degradation.Compared with normal poly-Si TFTs,the dynamic HC degradation of BG poly-Si TFTs under the same stress is greatly reduced.By selectively doping the active channel,the multiple PN junctions inherent can effectively share the voltage drop,resulting in better dynamic HC reliability.Based on transient simulations,the related degradation mechanism is clarified.All test results indicate that such high-performance and highly reliable BG poly-Si TFTs have great potential in system-on-panel applications.