A Novel Heat Dissipation Structure for Inhibiting Hydrogen Diffusion in Top-Gate a-InGaZnO TFTs

• Published in: IEEE electron device letters Vol. 40; no. 9; pp. 1447 - 1450
• Main Authors: Chen, Hong-Chih, Chen, Guan-Fu, Chen, Po-Hsun, Huang, Shin-Ping, Chen, Jian-Jie, Zhou, Kuan-Ju, Kuo, Chuan-Wei, Tsao, Yu-Ching, Chu, An-Kuo, Huang, Hui-Chun, Lai, Wei-Chih, Chang, Ting-Chang
• Format: Journal Article
• Language: English
• Published: New York IEEE 01.09.2019; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Degradation; Diffusion; Heating; Heating systems; High temperature effects; Hump effect; Hydrogen; hydrogen diffusion; Indium gallium zinc oxide; Logic gates; self-heating stress (SHS); Semiconductor devices; Stress; Temperature effects; Thin film transistors; thin-film transistor (TFT); Threshold voltage
• ISSN: 0741-3106; 1558-0563
• DOI: 10.1109/LED.2019.2927422

In order to better understand the reliability issues in top-gate a-InGaZnO (a-IGZO) thin-film transistors, this letter investigates the degradation mechanism of a device under self-heating stress (SHS). After applying hot carrier stress, a negative threshold voltage (<inline-formula> <tex-math notation="LaTeX">{V} _{\text {TH}} </tex-math></inline-formula>) shift, a hump effect, and normally- ON current degradation were found. COMSOL simulation results of hydrogen diffusion in the source and drain (n + region) of a-IGZO show that Joule heat was generated in the channel during SHS, which leads to hydrogen diffusion in the central and side channels. The unequal channel thermal effect results in a hump effect in the electrical characteristics, and the self-heating effect becomes more prominent as the channel width increases. To minimize the effects of these abnormal phenomena under high current operation in future display applications, a method of creating structural divisions in the channel width is used to aid overall heat dissipation and reduce the effect of SHS degradation.