Enhanced Electrical Properties and Stability in IGZO TFTs via Low-Temperature Activation with MgOx Layer.

Abstract

We propose the introduction of a magnesium oxide (MgOx) layer to reduce the temperature required for the activation of indium gallium zinc oxide (IGZO) thin films. By incorporating the MgOx layer between the IGZO channel layer and the gate insulator layer, the required activation temperature is lowered from 300 to 200 °C while enhancing the electrical performance of the IGZO thin-film transistor (TFT). Specifically, the field effect mobility is improved from 6.40 to 16.12 cm2/(V s), the on/off current ratio is enhanced from 1.62 × 109 to 7.16 × 109, and subthreshold swing is enhanced from 0.48 to 0.46 V/decade. Furthermore, IGZO TFTs with the MgOx layer exhibit enhancements in threshold voltage (VTH) shift compared to TFTs without the MgOx layer under positive bias stress (VGS = 20 V and VDS = 0.1 V for 10,000 s) and negative bias stress (VGS = -20 V and VDS = 0.1 V for 10,000 s): the VTH shifts are decreased from 2.40 to 1.72 V and from 0.56 to 0.53 V, respectively. These enhancements are verified through various analyses and are attributed to the diffusion of Mg atoms into the IGZO front channel during the low-temperature activation process, which results in the formation of Mg-doped IGZO between the MgOx and IGZO channel layers.