A semiconductor device and a method of fabricating the same. In accordance with a method of fabricating a semiconductor device according to an aspect of the invention, a tunnel dielectric layer, a first conductive layer, a dielectric layer, a second conductive layer, and a gate electrode layer are sequentially stacked over a semiconductor substrate. The gate electrode layer and the second conductive layer are patterned. A first passivation layer is formed on sidewalls of the gate electrode layer. Gate patterns are formed by etching the dielectric layer, the first conductive layer, and the tunnel dielectric layer, which have been exposed. A second passivation layer is formed on the entire surface along a surface of the gate patterns including the first passivation layer.