Application of DC Magnetron Sputtering to Deposition of InGaZnO Films for Thin Film Transistor Devices

This is the first report demonstrating that InGaZnO (IGZO) thin films deposited using DC magnetron sputtering can be used for the active channel layer of a thin film transistor (TFT) device. We have determined the process conditions at which dc magnetron sputtering provides a high growth rate and smooth surface for IGZO thin films using an InGaZnO(4) ceramic target. The effect of the oxygen content on the electrical properties of the IGZO thin films was examined. The field effect mobility of the TFT device fabricated with the IGZO thin film deposited at an optimum oxygen partial pressure of 6% was 9.2 cm(2) V(-1) s(-1). The operation mechanism of IGZO-TFT was explained on the basis of the band diagram with flat band voltage. Moreover, we evaluated the effects of bias stress on transistor performance and showed that device instability appears to be a result of the carrier trapping and releasing in the gate insulator layer under high gate voltage stress. (C) 2009 The Japan Society of Applied PhysicsThe HR-TEM analysis was performed at the National Nanofab Center at Daejeon with the help of Dr. Jung Ho Yoo. This work was Supported by Samsung Electronics Co. through the Brain Korea 21 project Under the Ministry of Education and Human Resources Development