High temperature failure modes of In2O3 thin films and improved thermal stability using Al2O3/ZrO2 protective layers

Abstract The limiting temperature of an In2O3 thin film sensor is much lower than its melting point. Herein, the failure modes of In2O3 thin films at high temperatures, including sublimation and changes in composition, have been studied. The edge and surface layer sublimation rates increased dramatically at 1350 °C, indicating that it is the limiting temperature of no-protection In2O3 films. In addition, oxygen atoms will escape from In2O3 thin films at high temperatures, forming oxygen vacancies. As the main current carrier type in In2O3, the increasing number of oxygen vacancies affects the resistance of In2O3 thin film sensors. To solve these problems and promote the high temperature performance of In2O3 thin films, protection methods based on Al2O3 and ZrO2 layers have been investigated. The ZrO2 protective layer alleviated the serious considerable sublimation of In2O3 thin films at high temperatures, and the Al2O3 protective layer was beneficial for reduction the escape of oxygen atoms. Finally, different protection layers were evaluated by in-situ resistivity measurements of In2O3 thin films at high temperatures. The resistance of the In2O3 thin film resistor with a protective multilayer consisting of Al2O3 and ZrO2 remained stable at 1360 °C, verifying the protection method effectively increased the thermal stability of In2O3 thin films.