Nonvolatile semiconductor memory device and method for manufacturing same

Abstract

Nonvolatile semiconductor memory devices and methods for manufacturing thereof, which provide inhibiting the shortcutting of the channel due to the creation of the bird's beak to promote the manufacturing of the devices with higher-density or higher-integration, lowering the operation voltage and improving the characteristics of maintaining the electric charge, without complicating the manufacturing process. Immediately after forming an ONO films comprising a first silicon oxide film, a second silicon nitride film and a third silicon oxide film on a silicon substrate, a silicon layer is formed, and then, arsenic ions are implanted over the silicon layer and/or ONO films to form a bit line, and a second electrical conductive layer is deposited while remaining the silicon layer to form a word line comprising a dual layer structure of two electrical conductive layers.