Abstract: Disclosed are a semiconductor device with dual gate dielectric layers and a method for fabricating the same. The semiconductor device includes: a silicon substrate divided into a cell region where NMOS transistors are formed and a peripheral region where NMOS and PMOS transistors are formed; a targeted silicon oxide layer formed on the silicon substrate in the cell region; an oxynitride layer formed on the silicon substrate in the peripheral region; a first gate structure formed in the cell region; a second gate structure formed on the oxynitride layer in an NMOS region of the peripheral region; and a third gate structure formed on the oxynitride layer in a PMOS region of the peripheral region.