Dynamic Negative Bias Temperature Instability (NBTI) of Low-Temperature Polycrystalline Silicon (LTPS) Thin-Film Transistors

The dynamic negative bias temperature instability (NBTI) on low-temperature polycrystalline silicon thin-film transistors (LTPS TFTs) was investigated in detail. Experimental results revealed the threshold voltage shift of LTPS TFTs after the NBTI stress decreases with increasing frequency, which is different from the frequency-independence of conventional CMOSFET. Under a low frequency stress, the capacitance-voltage measurement with various frequencies implied that a larger quantity of inversion holes was trapped in the grain boundary. Thus, the difference of the transit time between the grain boundary and interface dominates the LTPS TFTs dynamic NBTI behaviors and results in the dependence of frequency.