Vertical transistor and manufacturing method thereof

A vertical transistor and a manufacturing method thereof are provided herein. The manufacturing method includes forming a first patterned conductive layer on a substrate; forming a patterned metal oxide layer on the first patterned conductive layer, in which the patterned metal oxide layer includes a first patterned insulator layer, a second patterned insulator layer, and a second patterned conductive layer; forming a semiconductor layer; and forming a third patterned conductive layer. The first patterned insulator layer, the second patterned insulator layer, and the second patterned conductive layer are made by using a single metal oxide material. The oxygen concentration of the second patterned conductive layer is different from the oxygen concentrations of the first patterned insulator layer and the second patterned insulator layer.