Memory device and manufacturing method thereof

Abstract

A memory device and a manufacturing method thereof are provided. The memory device includes an access transistor defined within an active region of a semiconductor substrate and a storage capacitor disposed on the access transistor. A recessed gate structure of the access transistor extends into the active region from above the active region. Source/drain contacts of the access transistor are disposed on the active region at opposite sides of the recessed gate structure. The storage capacitor includes: a composite bottom electrode, formed by alternately stacked first conductive layers and second conductive layers, wherein each second conductive layer is sandwiched between a pair of the first conductive layers, and tunnels laterally extend through the second conductive layers, respectively; a capacitor dielectric layer, covering inner and outer surfaces of the composite bottom electrode; and a top electrode, in contact with the composite bottom electrode through the capacitor dielectric layer.