氧分压对铟镓锌氧薄膜晶体管性能影响

摘要

采用标准的液晶显示屏基板制备工艺制备出铟镓锌氧薄膜晶体管(IGZO-TFT),通过调节 IGZO 薄膜工艺中氧分压,研究不同氧分压对TFT器件电学性能的影响.实验结果表明,所有器件都展现出良好的电学特性,随着氧分压从10％增加到50％,TFT的阈值电压由0．5 V增加到2．2 V,而亚阈值摆幅没有发生变化.在栅极施加30 V偏压3600 s后,随着氧分压的增加,阈值电压向正向的漂移量由1 V增加到9 V.经过分析得出高氧分压的 IGZO-TFT器件中载流子浓度低,建立相同导电能力的沟道时所需要栅极电压会更大,阈值电压会增加.而在金属-绝缘层-半导体(MIS)结构中低载流子浓度会导致有源层能带弯曲的部分包含更多与电子陷阱相同的能态,栅介质层(GI)会俘获更多的电子,造成阈值电压漂移量较大的现象.%Indium gallium zinc oxide thin film transistors (IGZO-TFT)were fabricated with the stand-ard process of TFT-LCD arrays substrate.The effects of different oxygen partial pressure on IGZO-TFT performance were investigated by adj usting the oxygen partial pressure in IGZO film process.All devices showed good electrical properties.The threshold voltage of TFT was increased from 0.5 V to 2.2 V as the oxygen partial pressure was increased from 10% to 50%,whereas the sub-threshold swing had not changed.Applying a positive gate bias of 30 V for 3 600 s,with the increase of the oxy-gen partial pressure,the positive shift of threshold voltage of IGZO-TFT was increased from 1 V to 9 V.The carrier concentration in TFT with higher oxygen partial pressure is lower.So it requires high-er gate voltage for building the channel with the same conductive capability,and therefore the thresh-old voltage will be higher.In the Metal-Insulator-Semiconductor (MIS)structure,the lower carrier concentration leads electron accumulation layer to be thicker.There will be more energy states in band bending part of active layer which are the same as electron traps of gate insulator (GI).Consequently, it is possible that more electrons are captured by GI,and shift of threshold voltage will be greater.