Disclosed is a semiconductor package with Pillar-Top-Interconnection (PTI) configuration, comprising a redistribution layer (RDL) formed on a carrier plane, a plurality of metal pillars disposed on the RDL, a chip bonded onto the RDL, and a molding core. The molding core is formed on the carrier plane and has a bottom surface defined by the carrier plane so that the RDL is embedded inside the molding core. The package thickness of the molding core is greater than the chip-bonding height of the chip so that the chip is completely embedded inside the molding core. The metal pillars are encapsulated at the peripheries of the molding core with a plurality of pillar top portions exposed from the molding core. The exposed pillar top portions are reentrant from a top surface of the molding core and uneven. Accordingly, it realizes the effects of ultra-thin and smaller footprint POP stacked assembly with fine pitch vertically electrical connections in POP structure. Also, it is possible to achieve zero spacing between POP stacked assembly.