A method of manufacturing a semiconductor device includes providing a first semiconductor chip comprising a first metallic structure, a first surface and a second surface opposite to the first surface; providing a second semiconductor chip comprising a second metallic structure; bonding the first semiconductor chip with the second semiconductor chip on the second surface; forming a first recessed portion including a first sidewall and a first bottom surface coplanar with a top surface of the first metallic structure; forming a second recessed portion including a second sidewall and a second bottom surface coplanar with a top surface of the second metallic structure; forming a dielectric layer over the first sidewall and the second sidewall; and forming a conductive material over the dielectric layer, the top surface of the first metallic structure and the top surface of the second metallic structure.