A method for fabricating a semiconductor package, the method including: forming a release layer on a first carrier substrate, wherein the release layer includes a first portion and a second portion, wherein the first portion has a first thickness, and the second portion has a second thickness thicker than the first thickness; forming a barrier layer on the release layer; forming a redistribution layer on the barrier layer, wherein the redistribution layer includes wirings and an insulating layer; mounting a semiconductor chip on the redistribution layer; forming a molding layer on the redistribution layer to at least partially surround the semiconductor chip; attaching a second carrier substrate onto the molding layer; removing the first carrier substrate and the release layer; removing the barrier layer; and attaching a solder ball onto the redistribution layer exposed by removal of the barrier layer and the second portion of the release layer.