A method of fabricating a semiconductor device. A cell area and a core area is defined in a substrate. A bit line structure disposed in the cell area is provided. A gate structure disposed in the core area is provided, and a core capping film disposed on the gate structure is provided. A height of the core capping film is greater than a height of the bit line structure. A first contact film is formed on the bit line structure. A second contact film is formed on the core capping film. A mask is formed on the first contact film. An upper surface of the core capping film is exposed using the mask. The first contact film is etched until a height of the first contact film becomes less than a height of the bit line structure using an etching process. In the etching process, an etching rate for the first contact film is greater than etching rates for the bit line structure and the core capping film.