SEMICONDUCTOR MEMORY DEVICE

A semiconductor memory device may have a substrate including an active region in a memory cell region and a logic active region in a peripheral region, an element isolation structure between the active region and the logic active region, an insulating layer pattern covering the active region, and a support insulating layer. The insulating layer pattern may include an extension portion that extends along the element isolation structure, may be spaced apart from the element isolation structure, and may overhang over the element isolation structure. The support insulating layer may fill a recess space defined between the extension portion and the element isolation structure.