Semiconductor structure and method for preparing the same

The present disclosure provides a semiconductor structure and a method preparing it. After planarization of the Cu layer, a Si substrate is dry etched, so that a first height difference is configured in between the top surfaces of the the Si substrate and an insulating layer. By means of a wet etch process, Cu residues near an edge of a Cu post may be effectively removed. A second height difference is configured in between the top surfaces of the Cu post and the insulating layer. The first height difference is arranged to be greater than the second height difference. Channeling of Cu trace residues through the insulating layer are thereby avoided, effectively mitigating electrical leakage. Further, the Si substrate may be covered by a passivation layer, to prevent a conductive channel from being formed on the Si substrate, thereby further avoiding negative impact on the electrical properties of the device.