A method for fabricating an electrical interconnect structure is adapted for a circuit board manufacturing process. The circuit board comprises a conductive substrate, which comprises a first conductive layer and a bump conductive layer. The bump conductive layer is patterned to form at least one bump over the first conductive layer. Then, a dielectric layer is formed over the first conductive layer and the bump. A second conductive layer is formed over the dielectric layer. At least one blind hole is formed in the second conductive layer and the dielectric layer, passing through the second conductive layer and the dielectric layer to expose the top surface of the bump. A conductive material is filled in the blind hole, and the conductive material in the blind hole and the bump constitute a conductive post.