After first metal lines and a first inter-metal dielectric are formed on a semiconductor substrate, top surfaces thereof are planarized to construct a flat plane. Then, second metal lines each being vertically aligned with a corresponding first metal line are formed on the flat plane, so that integral metal lines of a high aspect ratio are constructed. Gaps formed by the second metal lines are filled with a second inter-metal dielectric, which is joined with the first inter-metal dielectric to construct an integral inter-metal dielectric.