METHOD OF FABRICATING SEMICONDUCTOR MEMORY DEVICE

A semiconductor memory device may be formed by a method of fabricating the same. The method may include forming a buffer insulating layer on a semiconductor substrate including active portions, forming bit line structures on the buffer insulating layer, forming bit line spacers on side surfaces of each of the bit line structures, patterning the buffer insulating layer to form gap regions extending in a first direction, the gap regions formed between the bit line structures and exposing portions of the active portions, forming a protection oxide layer to cover the portions of the active portions exposed through the gap regions, forming a mold layer to fill the gap regions, in which the protection oxide layer is formed, forming mold patterns respectively in each of the gap regions to be spaced apart from each other, forming fence patterns in each of the gap regions and between the mold patterns, removing the mold patterns to form contact regions exposing the protection oxide layer, removing the protection oxide layer, and forming buried contact patterns in the contact regions to contact the portions of the active portions.