A wiring structure includes a dielectric layer and a first patterned conductive layer on the dielectric layer. The dielectric layer has a first region and a second region. The first patterned conductive layer includes a number of fine conductive lines and a number of dummy conductive structures. The number of conductive lines include a first number of conductive lines on the first region and a second number of conductive lines on the second region, and the number of dummy conductive structures include a first number of dummy conductive structures on the second region. The first number of conductive lines occupy a first area on the first region, and the second number of conductive lines and the first number of dummy conductive structures occupy a second area on the second region. A ratio of the second area to the first area is greater than or equal to about 80%.