Oxide thin film transistors (TFTs) are widely used as backplane for displays such as active matrix organic light emitting diode display and active matrix liquid crystal display. And also, it can be used in many applications such as sensor and wearable devices which require small power consumption. For low power consumption, the operation voltage should be decreased and the vertical structure TFT is a candidate due to short channel length. In this study, we proposed a vertical structure TFTs using a thin gate dielectric.

In this experiment, a vertical structure TFTs with a channel formed on the vertical sidewall of the gate electrode and a channel length controlled by the thickness of the gate electrode is proposed. The channel length was adjusted by the thickness of the gate electrode in the vertical TFTs developed in this paper. Figure 1 shows the fabricated vertical a-IGZO TFT developed in this study.

This vertical TFTs has the feature of controlling the channel length by the thickness of the gate electrode and can achieve short channel length easily, which is useful for low driving voltage. To reduce the gate voltage also, the thin gate dielectric was used. Since the very thin gate insulator was used, low threshold voltage was obtained, and low voltage driving was possible.