Semiconductor structure and manufacturing method thereof

A manufacturing method of a semiconductor structure, comprising:

• (a) disposing a dam element on a substrate;
• (b) forming a trench through the substrate, such that the trench has a first opening at a first surface of the substrate, the trench has a second opening at a second surface of the substrate, and a sidewall of the substrate faces the trench;
• (c) forming a first isolation layer in the trench, such that a portion of the sidewall is covered by the first isolation layer;
• (d) forming a second isolation layer on the first isolation layer, the sidewall that is not covered by the first isolation layer, and the first surface, such that an interface is formed between the first and second isolation layers;
• (e) removing a portion of the second isolation layer, a portion of the first isolation layer, and a portion of the dam element in the trench, such that a concave portion is formed in the dam element, and an conductive pad of the substrate is exposed through the concave portion;
• and
• (f) forming a conductive layer on the concave portion, the first and second isolation layers, such the conductive layer electrically contacts the conductive pad.