Negative Bias Temperature Instability Dominated Degradation of Metal-Induced Laterally Crystallized p-Type Polycrystalline Silicon Thin-Film Transistors

Device degradation of solution-based metal-induced laterally crystallized p-type polycrystalline silicon (poly-Si) thin-film transistors (TFTs) is studied under dc bias stresses. While typical negative bias temperature instability (NBTI) or electron injection (EI) is observed under -V_g or -V_d only stress, respectively, no typical hot carrier (HC) degradation can be identified under high -V_d stress combined with either low or high -V_g stress. Instead, mixed NBTI and EI degradation is observed under combined low -V_g and -V_d stresses; and combined degradation of NBTI and HC occurs under high -V_d and moderate -V_g stresses. NBTI is the dominant mechanism in both cases. Grain boundary (GB) trap generation is found to correlate with the NBTI degradation with the same time exponent, suggesting the key role of GB trap generation in poly-Si TFTs´ degradation.