A semiconductor structure includes a semiconductor chip having at least an electrode pad, a first metal layer formed on the electrode pad, a second metal layer completely formed on and in contact with the first metal layer, and a conductive pillar disposed on the second metal layer, where a material of the first metal layer is different from a material of the second metal layer, the first metal layer has a first distribution-projected area larger than a second distribution projected-area of the conductive pillar, and the second metal layer has a third distribution-projected area that is the same as the second distribution-projected area of the conductive pillar.