Semiconductor device and method of manufacturing the same

A semiconductor device comprising:

• a semiconductor substrate;
• a trench formed in the semiconductor substrate;
• an island-like element region formed in the semiconductor substrate, having an upper surface, a first side surface exposed by the trench, a second side surface, and a third side surface opposing the second side surface, and having an upper portion including the upper surface, a middle portion positioned below the upper portion, and a lower portion positioned below the middle portion;
• a gate insulating film formed on the first to third side surfaces in the upper portion of the element region;
• a gate electrode having a portion extending over the upper surface of the element region and the second and third side surfaces in the upper portion of the element region, and having a first bottom surface positioned above the upper surface of the element region, and a second bottom surface positioned below the upper surface of the element region;
• a first diffusion layer formed along the upper surface of the element region;
• a second diffusion layer formed along the first side surface in the middle portion of the element region;
• a channel region having a first region formed along the first side surface in the upper portion of the element region, a second region formed along the second side surface in the upper portion of the element region, and a third region formed along the third side surface in the upper portion of the element region;
• a capacitor formed in the trench and adjacent to the lower portion of the element region;
• and
• a bit line electrically connected to the first diffusion layer.