Abnormal Threshold Voltage Shifts in P-Channel Low-Temperature Polycrystalline Silicon Thin Film Transistors Under Negative Bias Temperature Stress

作者：Kim Sang Sub; Choi Pyung Ho; Baek Do Hyun; Lee Jae Hyeong; Choi Byoung Deog^*

来源：Journal of Nanoscience and Nanotechnology, 2015, 15(10): 7555-7558.

DOI：10.1166/jnn.2015.11167

• LTPS TFTs
• Reliability
• Threshold Voltage
• NBTI

In this research, we have investigated the instability of P-channel low-temperature polycrystalline silicon (poly-Si) thin-film transistors (LTPS TFTs) with double-layer SiO2/SiNx dielectrics. A negative gate bias temperature instability (NBTI) stress was applied and a turn-around behavior phenomenon was observed in the Threshold Voltage Shift (V-th). A positive threshold voltage shift occurs in the first stage, resulting from the negative charge trapping at the SiNx/SiO2 dielectric interface being dominant over the positive charge trapping at dielectric/Poly-Si interface. Following a stress time of 7000 s, the V-th switches to the negative voltage direction, which is "turn-around" behavior. In the second stage, the V-th moves from -1.63 V to -2 V, overwhelming the NBTI effect that results in the trapping of positive charges at the dielectric/Poly-Si interface states and generating grain-boundary trap states and oxide traps.

• 出版日期2015-10