Preparation method of a thin power device

A preparation method of a thin power device comprising the steps of:

• Step S1, providing a substrate comprising a first set of first contact pads and a second set of second contact pads arranged at a front surface and a back surface of the substrate respectively, wherein each first contact pad in the first set of contact pads is electrically connected with a corresponding second contact pad in the second set of contact pads via a interconnecting structure formed inside the substrate;
• and a through opening formed in the substrate aligning with a third contact pad at the back surface of the substrate, wherein the third contact pad is not electrically connected with any first contact pad in the first set of contact pads exposes from the through opening;
• Step S2, embedding a semiconductor chip into the through opening, wherein a back metal layer at the back surface of the semiconductor chip is attached on the third contact pad in the second set of contact pads exposing in the through opening;
• and
• Step S3, electrically connecting each electrode at the front surface of the semiconductor chip with a first contact pad in the first set of contact pads via a plurality of conductive structures respectively.