A method for fabricating a capacitor includes following steps: providing a substrate and a first conducting material layer which is disposed on the substrate; removing a part of the first conducting material layer to expose a part of the substrate to form a plurality of first inner electrodes, wherein the first inner electrodes are arranged along a first direction, and the adjacent first inner electrodes have an interval therebetween; forming a dielectric layer along a second direction by a chemical vapor deposition process, wherein the first direction is perpendicular to the second direction so that the dielectric layer covers the first inner electrodes and the exposed part of the substrate, and the dielectric layer does not fully fill the intervals; and forming a second conducting material layer to fill the intervals that are not fully filled by the dielectric layer to form a plurality of second inner electrodes.