The memory device is described, which includes a substrate, a conductive layer, a plurality of charge storage layers and a plurality of doped regions. The substrate has a plurality of trenches formed therein. The conductive layer is disposed on the substrate and fills the trenches. The charge storage layers are disposed between the substrate and the conductive layer in the trenches respectively, wherein the charge storage layers are separated from each other. The doped regions are configured in the substrate under bottoms of the trenches, respectively.