Semiconductor device and method of manufacturing the same

In one embodiment, a semiconductor device includes a substrate including a trench, and a gate electrode disposed at a position adjacent to the trench on the substrate, the gate electrode having a first side surface located on an opposite side of the trench, and a second side surface located on the same side as the trench. The device further includes a first sidewall insulator disposed on the first side surface, and a second sidewall insulator disposed on the second side surface and a side surface of the trench. The device further includes a source region of a first conductivity type disposed in the substrate on the same side as the first sidewall insulator with respect to the first side surface, and a drain region of a second conductivity type disposed in the substrate on the same side as the second sidewall insulator with respect to the second side surface.