Semiconductor devices and methods for fabricating the same are provided. An exemplary embodiment of a semiconductor device comprises a substrate with a plurality of isolation structures formed therein, defining first and second areas over the substrate. A transistor is formed on a portion of the substrate in the first and second areas, respectively, wherein the transistor in the second area is formed with merely a pocket doping region in the substrate adjacent to a drain region thereof. A first dielectric layer is formed over the substrate, covering the transistor formed in the first and second areas. A plurality of first contact plugs is formed through the first dielectric layer, electrically connecting a source region and a drain region of the transistor in the second area, respectively. A second dielectric layer is formed over the first dielectric layer with a capacitor formed therein, wherein the capacitor electrically connects one of the first contact plugs.