A semiconductor substrate includes: 1) a first dielectric structure having a first surface and a second surface opposite the first surface; 2) a second dielectric structure having a third surface and a fourth surface opposite the third surface, wherein the fourth surface faces the first surface, the second dielectric structure defining a through hole extending from the third surface to the fourth surface, wherein a cavity is defined by the through hole and the first dielectric structure; 3) a first patterned conductive layer, disposed on the first surface of the first dielectric structure; and 4) a second patterned conductive layer, disposed on the second surface of the first dielectric structure and including at least one conductive trace. The first dielectric structure defines at least one opening to expose a portion of the second patterned conductive layer.