Manufacturing method of substrate structure having embedded interconnection layers

A manufacturing method of substrate structure, comprising:

• providing a conductive carrier;
• forming a first photoresist layer on the conductive carrier, wherein the first photoresist layer is patterned to form a plurality of first openings exposing the conductive carrier;
• forming a first metal layer in the plurality of first openings;
• forming a second photoresist layer on the first photoresist layer and the first metal layer, wherein the second photoresist layer is patterned to form a plurality of second openings exposing the first metal layer;
• forming a third photoresist layer on the second photoresist layer, wherein the third photoresist layer is patterned to form a plurality of third openings exposing the plurality of second openings and a part of the second photoresist layer
• forming a second metal layer and a third metal layer in the plurality of second openings and the plurality of third openings at the same time;
• and
• removing the first photoresist layer, the second photoresist layer and the third photoresist layer, wherein the first metal layer, the second metal layer and the third metal layer form a conductive structure on the conductive carrier;
• wherein each of the second metal layer and the third metal layer has a first surface and a second surface opposite the first surface, the first surface of the third metal layer is connected to the second surface of the second metal layer, and a surface area of the first surface of the third metal layer is larger than a surface area of the second surface of the second metal layer.