A semiconductor package substrate may include a first semiconductor chip, a second semiconductor chip, plugs and interconnection terminals. The second semiconductor chip may be arranged on an upper surface of the first semiconductor chip. The first and second semiconductor chips may have corresponding first regions and corresponding second regions. Conductive plugs may be built only in a first region of the first semiconductor chip. Circuitry of the second semiconductor chip may only be electrically connected to the first semiconductor chip through the conductive connectors corresponding to the first regions of the first and second semiconductor chips.