Semiconductor devices and fabrication methods thereof. A first dielectric layer with a first conductor line along a first direction is disposed on a semiconductor substrate, wherein the top surface of the first conductor line is lower than the top surface of the first dielectric layer. A second dielectric layer comprising an opening corresponding to the first diode element is disposed on the first dielectric layer. A semiconductor diode component comprises a first diode element disposed on the first conductor line, wherein the top surface of the first diode element is level with the top surface of the first dielectric layer; and a second diode element and a third diode element are filled in the opening.