A capacitor includes a first electrode, a dielectric, and a second electrode. The first electrode is located on a dielectric layer. The dielectric covers the sidewall and the top surface of the first electrode. The second electrode covers the dielectric and the dielectric layer, wherein the orthographic projection area of the second electrode on the dielectric layer is greater than the orthographic projection area of the first electrode on the dielectric layer. The capacitor of the invention has good reliability.