A semiconductor device includes a substrate, a first redistribution layer (RDL) over a first side of the substrate, one or more semiconductor dies over and electrically coupled to the first RDL, and an encapsulant over the first RDL and around the one or more semiconductor dies. The semiconductor device also includes connectors attached to a second side of the substrate opposing the first side, the connectors being electrically coupled to the first RDL. The semiconductor device further includes a polymer layer on the second side of the substrate, the connectors protruding from the polymer layer above a first surface of the polymer layer distal the substrate. A first portion of the polymer layer contacting the connectors has a first thickness, and a second portion of the polymer layer between adjacent connectors has a second thickness smaller than the first thickness.