In some embodiments, a contact via and a fabricating method thereof are provided. The method can comprise: providing a substrate; forming a buffer layer in the substrate; forming a dielectric layer covering the substrate and the buffer layer; forming a through hole in the dielectric layer, wherein a bottom of the through hole exposes a surface of the buffer layer; performing a roughening treatment to the exposed surface of the buffer layer to increase a roughness of the exposed surface of the buffer layer; forming a barrier layer in the through hole, and reducing a thickness of a portion of the barrier layer at the bottom of the through hole; and filling a conductive material into the through hole to form a contact via.