Abstract: A semiconductor package and a fabrication method thereof are provided. During a molding process, a substrate mounted with a chip is placed in a mold having a molding cavity, wherein the molding cavity is sized larger than the predetermined size of the semiconductor package, and a portion of the mold for clamping the substrate is located outside a circuit layout area of the substrate. Thereby, an encapsulant subsequently formed for encapsulating the chip is sized larger than the predetermined size of the semiconductor package. Then, a singulation process is performed to remove portions of the encapsulant and portions of the substrate unit larger in size than the predetermined size of the semiconductor package, such that damage to circuits of the substrate can be prevented. Further, during the fabrication processes, a heat sink may be mounted on the chip to form a thermally enhanced semiconductor package.