A semiconductor structure and a method for fabricating the same are provided. The semiconductor structure includes a wafer substrate having a top surface and a bottom surface, and a conductive pillar in the wafer substrate defined by a deep trench insulator through the top surface and the bottom surface of the wafer substrate. The method for fabricating the semiconductor structure includes following steps. A deep trench is formed from a top surface of a wafer substrate to define a conductive region in the wafer substrate. The conductive region is doped with a dopant. The deep trench is filled with an insulation material to form a deep trench insulator. And the wafer substrate is thinned from a bottom surface of the wafer substrate to expose the deep trench insulator and isolate the conductive region to form a conductive pillar.