Abstract: A semiconductor memory device includes a semiconductor substrate having a trench therein. First and second gate patterns are formed on a surface of the substrate adjacent the trench, a respective one of which is on a respective opposing side of the trench. A split source/drain region is formed in the substrate between the first gate pattern and the second gate pattern such that the split source/drain region is divided by the trench. The split source/drain region includes a first source/drain subregion between the first gate pattern and the trench and a second source/drain subregion between the second gate pattern and the trench and spaced apart from the first source/drain subregion. A connecting region is formed in the substrate that extends around the trench from the first source/drain subregion to the second source/drain subregion. Related methods are also discussed.