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

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 (V
_TH
) 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.