A semiconductor device and the method of manufacturing the same are provided. The semiconductor device comprises a well region, a first doped region, a drain region, a source region and a gate electrode. The first doped region of a first conductivity type is located at a first side within the well region. The drain region of the first conductivity type is within the first doped region. The source region of the first conductivity type is at a second side within the well region, wherein the second side being opposite to the first side. The gate electrode is over the well region and between the source region and the drain region. A surface of the drain region and a surface of the source region define a channel and the surface of the source region directly contacts the well region.