Effects of various gate materials on electrical degradation of a-Si:H TFT in industrial display application

Ching Yuan Ho; Yaw Jen Chang

doi:10.1016/j.sse.2015.10.006

Effects of various gate materials on electrical degradation of a-Si:H TFT in industrial display application

Ching Yuan Ho, Yaw Jen Chang

Department of Mechanical Engineering

Research output: Contribution to journal › Article › peer-review

3 Citations (Scopus)

Abstract

Both aluminum (Al) and copper (Cu), acting as transmission lines in the hydrogenated amorphous silicon of a thin film transistor (a-Si:H TFT), were studied to investigate electrical degradation including electron-migration (EM) and threshold voltage (V_t) stability and recovery performance. Under long-term current stress, the Cu material exhibited excellent resistance to EM properties, but a passivated SiN_x crack was observed due to fast heat conductivity. By applying electrical stress on the gate and drain for 5 × 10⁴ s, the power-law time dependency of the threshold voltage shift (ΔV_t) indicated that the defective state creation dominated the TFT device's instability. The presence of drain stress increased the overall ΔV_t because the high longitudinal field induced impact ionization and then, enhanced hot-carrier-induced electron trapping within the gate SiN_x dielectric. An annealing effect prompted a stressed a-Si:H TFT back to virgin status. This study proposes better ΔV_t stability and excellent resistance against electron-migration in a Cu gate device which can be considered as a candidate for a transmission line on prolonged TFT applications.

Original language	English
Pages (from-to)	130-134
Number of pages	5
Journal	Solid-State Electronics
Volume	116
DOIs	https://doi.org/10.1016/j.sse.2015.10.006
Publication status	Published - 2016 Feb

All Science Journal Classification (ASJC) codes

Electronic, Optical and Magnetic Materials
Condensed Matter Physics
Electrical and Electronic Engineering
Materials Chemistry

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title = "Effects of various gate materials on electrical degradation of a-Si:H TFT in industrial display application",

abstract = "Both aluminum (Al) and copper (Cu), acting as transmission lines in the hydrogenated amorphous silicon of a thin film transistor (a-Si:H TFT), were studied to investigate electrical degradation including electron-migration (EM) and threshold voltage (Vt) stability and recovery performance. Under long-term current stress, the Cu material exhibited excellent resistance to EM properties, but a passivated SiNx crack was observed due to fast heat conductivity. By applying electrical stress on the gate and drain for 5 × 104 s, the power-law time dependency of the threshold voltage shift (ΔVt) indicated that the defective state creation dominated the TFT device's instability. The presence of drain stress increased the overall ΔVt because the high longitudinal field induced impact ionization and then, enhanced hot-carrier-induced electron trapping within the gate SiNx dielectric. An annealing effect prompted a stressed a-Si:H TFT back to virgin status. This study proposes better ΔVt stability and excellent resistance against electron-migration in a Cu gate device which can be considered as a candidate for a transmission line on prolonged TFT applications.",

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AU - Ho, Ching Yuan

AU - Chang, Yaw Jen

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N2 - Both aluminum (Al) and copper (Cu), acting as transmission lines in the hydrogenated amorphous silicon of a thin film transistor (a-Si:H TFT), were studied to investigate electrical degradation including electron-migration (EM) and threshold voltage (Vt) stability and recovery performance. Under long-term current stress, the Cu material exhibited excellent resistance to EM properties, but a passivated SiNx crack was observed due to fast heat conductivity. By applying electrical stress on the gate and drain for 5 × 104 s, the power-law time dependency of the threshold voltage shift (ΔVt) indicated that the defective state creation dominated the TFT device's instability. The presence of drain stress increased the overall ΔVt because the high longitudinal field induced impact ionization and then, enhanced hot-carrier-induced electron trapping within the gate SiNx dielectric. An annealing effect prompted a stressed a-Si:H TFT back to virgin status. This study proposes better ΔVt stability and excellent resistance against electron-migration in a Cu gate device which can be considered as a candidate for a transmission line on prolonged TFT applications.

AB - Both aluminum (Al) and copper (Cu), acting as transmission lines in the hydrogenated amorphous silicon of a thin film transistor (a-Si:H TFT), were studied to investigate electrical degradation including electron-migration (EM) and threshold voltage (Vt) stability and recovery performance. Under long-term current stress, the Cu material exhibited excellent resistance to EM properties, but a passivated SiNx crack was observed due to fast heat conductivity. By applying electrical stress on the gate and drain for 5 × 104 s, the power-law time dependency of the threshold voltage shift (ΔVt) indicated that the defective state creation dominated the TFT device's instability. The presence of drain stress increased the overall ΔVt because the high longitudinal field induced impact ionization and then, enhanced hot-carrier-induced electron trapping within the gate SiNx dielectric. An annealing effect prompted a stressed a-Si:H TFT back to virgin status. This study proposes better ΔVt stability and excellent resistance against electron-migration in a Cu gate device which can be considered as a candidate for a transmission line on prolonged TFT applications.

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