Oxide thin film transistors (TFTs) have attracted much attention for potential applications in active- matrix organic light emitting displays(AMOLED) and liquid crystal displays (LCDs) due to the advantages of higher mobility than amorphous silicon TFT. Currently, oxide TFTs are being used in OLED TV and efforts are focused on improving electrical stability and process reliability. For mobile applications such as biosensors and wearable applications, low power consumption is required.

Much research is underway to realize biosensors and wearable devices with low power consumption, and very thin insulating films are needed. A thin insulating film can be formed by several ways and much more simple process is required.

With thin gate insulator it’s possible to reduce the operation voltages, which reduces the power consumption. The thin gate insulator was applied to the top gate amorphous oxide TFT as shown in Fig. 1. An IGZO active layer was deposited by RF sputtering and patterned. After gate pattern with thin gate insulator, source/drain region of IGZO layer was doped by oxygen plasma. The source/drain metal was deposited by DC magnetron sputtering and patterned. The operation voltage below 0.5 V was accomplished.