A ZnO-based thin film transistor (TFT) is provided herein, as is a method of manufacturing the TFT. The ZnO-based TFT has a channel layer that comprises ZnO and ZnCl, wherein the ZnCl has a higher bonding energy than ZnO with respect to plasma. The ZnCl is formed through the entire channel layer, and specifically is formed in a region near THE surface of the channel layer. Since the ZnCl is strong enough not to be decomposed when exposed to plasma etching gas, an increase in the carrier concentration can be prevented. The distribution of ZnCl in the channel layer, may result from the inclusion of chlorine (Cl) in the plasma gas during the patterning of the channel layer.