A memory device and a method of fabricating the same are provided. The method includes forming a gate stack on a semiconductor substrate and partially exposing upper end portions of the semiconductor substrate by etching the gate stack to form a gate stack structure, and implanting a dopant into the exposed portions of the semiconductor substrate to form source and drain regions, wherein the gate stack structure is etched such that its width increases from top to bottom. Accordingly, it is possible to manufacture a memory device with high integration, using a simplified manufacture process.