SEMICONDUCTOR DEVICE

A semiconductor device includes a substrate including first and second surfaces opposing each other. A device isolation layer extends through the substrate and defines an active region in the substrate. A gate electrode is on the first surface of the substrate. A wiring structure electrically connects the gate electrode and the active region. The active region includes a target doped region between the device isolation layer and the gate electrode and including a dopant having a first concentration. A path doped region is between the device isolation layer and the gate electrode and extends from the second surface of the substrate to the target doped region. The path doped region includes a dopant having a second concentration less than the first concentration. The target doped region and the path doped region are formed by implanting the dopant through the second surface of the substrate.