A semiconductor structure and a method of fabricating thereof are provided. The method includes the following steps. A substrate with an upper surface and a lower surface is received. A first recess extending from the upper surface to the lower surface is formed and the first recess has a first depth. A second recess extending from the upper surface to the lower surface is formed and the second recess has a second depth less than the first depth. A first conducting layer is formed in the first recess and the second recess. A first insulating layer is formed over the first conducting layer. A second conducting layer is formed over the first insulating layer and isolated from the first conducting layer with the first insulating layer. The substrate is thinned from the lower surface to expose the second conducting layer in the first recess.