A carrier substrate includes a circuit structure layer, a first solder resist layer, a second solder resist layer and conductive towers. The circuit structure layer includes a core structure layer, a first circuit layer and a second circuit layer. The first solder resist layer has first openings exposing a portion of the first circuit layer. The second solder resist layer has second openings exposing a portion of the second circuit layer. The conductive towers are disposed at the first openings, higher than a surface of the first solder resist layer and connected with the first openings exposed by the first circuit layer, wherein a diameter of each of the conductive towers gradually increases by a direction from away-from the first openings towards close-to the first openings. A diameter of the second conductive towers is greater than that of the first conductive towers.