A stacked semiconductor device primarily comprises semiconductor packages with a plurality of micro contacts and solder paste to soldering the micro contacts. Each semiconductor package comprises a substrate and a chip disposed on the substrate. The micro contacts of the bottom semiconductor package are a plurality of top bumps located on the upper surface of the substrate. The micro contacts of the top semiconductor package are a plurality of bottom bumps located on the lower surface of the substrate. The bottom bumps are aligned with the top bumps and are electrically connected each other by the solder paste. Therefore, the top bumps and the bottom bumps have the same soldering shapes and dimensions for evenly soldering to avoid breakages of the micro bumps during stacking.