A method for manufacturing a transistor includes forming a semiconductor layer on a substrate, a first insulation film on the semiconductor layer, and a gate electrode on the first insulation film. The method also includes forming a source region, a channel region, and a drain region in the semiconductor layer and forming a second insulation film on the gate electrode. A source electrode and a drain electrode are formed on the second insulation film and are coupled to the source region and the drain region, respectively. The method further includes coupling the drain electrode to the gate electrode through a contact hole that is vertically above the channel region.