Stability of thin film transistors incorporating a zinc oxide or indium zinc oxide channel deposited by a high rate sputtering process

A novel rf sputtering technology in which a high density plasma is created in a remote chamber has been used to reactively deposit zinc oxide (ZnO) and indium zinc oxide (IZO) thin films at room temperature from metallic sputtering targets at deposition rates similar to 50 nm min(-1), which is approximately an order of magnitude greater than that of rf magnetron sputtering. Thin film transistors have been fabricated using IZO with a maximum processing temperature of 120 degrees C, which is defined by the curing of the photoresist used in patterning. Devices have a saturated field effect mobility of 10 cm(2) V-1 s(-1) and a switching ratio in excess of 10(6). Gate bias stress experiments performed at elevated temperatures show a consistent apparent increase in the field effect mobility with time, which is attributed to a charge trapping phenomenon.