Analysis of Distinct Degradation Behavior in LTPS TFTs Under Hot Carrier Condition with Varying Gate Voltage

• Main Authors: Tu, Hong-Yi, Chang, Ting-Chang, Tsai, Tsung-Ming, Sun, Li-Chan, Kuo, Chen-Wei, Wu, Chia-Chuan, Chien, Ya-Ting
• Format: Conference Proceeding
• Language: English
• Subjects: Degradation; Heating systems; Hot Carrier (HC); Hot carriers; Logic gates; Low-temperature Polycrystalline silicon (LTPS); Negative bias temperature instability; Negative Bias Temperature Instability (NBTI); Thermal variables control; Thin Film Transistor (TFT); Thin film transistors
• ISSN: 1946-1550
• DOI: 10.1109/IPFA61654.2024.10691163

In this research, a distinct degradation behavior is observed in the low-temperature polycrystalline-silicon thin-film transistor under hot carrier condition with varying driving gate voltages. The factor causing this distinct degradation behavior can be generalized into two terms. The first term is the gate-to-drain voltage, which dominates the degree of impact ionization, controlling the generation of electron-hole pairs. Furthermore, the gate-to-drain voltage also influences the distribution of electric field direction and strength at the drain edge, governing the trapping of electrons into the gate insulator at the drain edge and at the buffer. The second factor contributing to the distinct degradation behavior is the stress current induced thermal in the channel. The current flowing in the channel induces Joule heating, leading to the occurrence of negative bias temperature instability in the channel. Consequently, higher driving currents exacerbate the degradation associated with negative bias temperature instability. In summary, the degradation behavior in the low-temperature polycrystalline-silicon thin-film transistor under hot carrier conditions with varying driving gate voltages is influenced simultaneously by the gate-to-drain voltage and the driving current.