A semiconductor chip includes a semiconductor substrate; a plurality of low-k dielectric layers over the semiconductor substrate; a first passivation layer over the plurality of low-k dielectric layers; and a second passivation layer over the first passivation layer. A first seal ring is adjacent to an edge of the semiconductor chip, wherein the first seal ring has an upper surface substantially level to a bottom surface of the first passivation layer. A second seal ring is adjacent to the first seal ring and on an inner side of the semiconductor chip than the first seal ring. The second seal ring includes a pad ring in the first passivation layer and the second passivation layer. A trench ring includes at least a portion directly over the first seal ring. The trench ring extends from a top surface of the second passivation layer down to at least an interface between the first passivation layer and the second passivation layer.