Stack-type multi-chips package and method for fabricating bumps on a backside surface of a chip

A stack-type multi-chips package includes a substrate, a first chip, a second chip, multiple bump pads, multiple bumps, multiple first wires, multiple second wires and a molding compound. The first chip is mounted on the substrate via a backside surface thereof. The second chip is mounted on an active surface of the first chip via a backside surface thereof. The bump pads are formed on the backside surface of the second chip. The bumps are positioned between the first chip and the second chip and connects the bump pads and the first chip. The first chip and the second chip are electrically connected to the substrate via the first wires and the second wires, respectively. The molding compound encapsulates the first chip, the second chip, the bumps, the first wires and the second wires.