In one aspect, a method for manufacturing a three-dimensional (3D) semiconductor device is disclosed. It includes providing a vertical stack of alternating layers of a first layer type and a second layer type, and providing a first trench and a second trench adjacent the vertical stack. The first trench and the second trench can define a fin. The method further can include recessing the first layer type to form recesses extending into the fin, providing a first electrode in individual ones of the recesses, and providing a second electrode in the first trench and the second trench. The method further can include providing, for individual ones of the recesses, a lateral stack including a memory element, a middle electrode, and a selector element. The lateral stack can extend between the first electrode and the second electrode, thereby forming a memory device.