Package on package structure and fabrication method thereof

A method for fabricating a package on package (PoP) structure is provided, which includes: providing a first packaging substrate having at least a first electronic element and a plurality of first support portions, wherein the first electronic element is electrically connected to the first packaging substrate; forming an encapsulant on the first packaging substrate for encapsulating the first electronic element and the first support portions; forming a plurality of openings in the encapsulant for exposing portions of surfaces of the first support portions; and providing a second packaging substrate having a plurality of second support portions and stacking the second packaging substrate on the first packaging substrate with the second support portions positioned in the openings of the encapsulant and bonded with the first support portions. As such, the encapsulant effectively separates the first support portions or the second support portions from one another to prevent bridging from occurring therebetween.