An interconnect structure including a substrate, at least one ultra-thick metal (UTM) layer, a first dielectric layer and at least one pad metal layer is provided. The at least one UTM layer is disposed on the substrate. The first dielectric layer is disposed on the at least one UTM layer and exposes the at least one UTM layer. A stress of the first dielectric layer is −150 Mpa to −500 Mpa. The at least one pad metal layer is disposed on the first dielectric layer and electrically connected to the at least one UTM layer exposed by the first dielectric layer.