Circuit board and fabricating method of the same

A fabricating method of a circuit board, comprising:

• providing a baseboard, wherein the baseboard comprises multiple first metal layers, a plated through hole and a filling material, wherein the multiple first metal layers are stacked, the plated through hole extends through the multiple first metal layers and is electrically connected to the multiple first metal layers, and the filling material is disposed in the plated through hole;
• forming a cover metal layer on the multiple first metal layers;
• forming a via hole on the cover metal layer to form a cover wiring layer, wherein the via hole reveals the filling material;
• after the via hole is formed, stacking a second metal layer on the cover wiring layer;
• after the second metal layer is stacked, forming a groove, wherein the groove extends through the cover wiring layer to part of the filling material from the second metal layer, wherein the groove overlaps the via hole;
• and
• forming a conductive structure in the groove, wherein the conductive structure is inserted in the filling material and is electrically connected to the second metal layer and the cover wiring layer.