Analysis of Negative Bias Temperature Instability in Body-Tied Low-Temperature Polycrystalline Silicon Thin-Film Transistors

Negative bias temperature instability (NBTI) degradation mechanism in body-tied low-temperature polycrystalline silicon thin-film transistors (LTPS TFTs) is analyzed by the charge-pumping (CP) technique. The properties of bulk trap states (including interface and grain boundary trap states) are directly characterized from the CP current. The increase of the fixed oxide charges is also extracted, which has not been quantified in previous studies of NBTI degradation in LTPS TFTs. The experimental results confirm that the NBTI degradation in LTPS TFTs is caused by the generation of bulk trap states and oxide trap states.