Disclosed is a method of fabricating a semiconductor package. The method may include providing a preliminary interposer substrate including connection terminals on a carrier substrate such that the connection terminals are oriented outward, preparing a release film including a base layer, an intermediate layer, and an adhesive layer, attaching the connection terminals to a first surface of the release film, detaching the carrier substrate from the preliminary interposer substrate, cutting the preliminary interposer substrate to form a plurality of interposer substrates separated from each other, irradiating a first light of a first wavelength onto the release film to form an air gap between the connection terminals and the release film, and detaching the interposer substrates from the release film. The intermediate substrate may include a light absorber absorbing the first light.