Provided is an erasable and programmable read only memory (EPROM) device in which a plasma enhanced oxide (PEOX) film covers an upper surface of a floating gate in a single poly one time programmable (OTP) cell and a method of manufacturing a semiconductor device having the same. The semiconductor device comprises a substrate having an OTP cell region, on which a floating gate is formed for making an OTP cell transistor, and a main chip region, on which a gate of a transistor is formed. A PEOX film is formed on the OTP cell region and the main chip region. The PEOX film covers the floating gate in a close state and covers the gate by a predetermined distance. A silicon oxy nitride (SiON) film Is interposed between the gate and the PEOX film in the main chip region.