For the purpose of providing a semiconductor and its manufacturing that can attain local smoothing by removing local defective surface morphology while attaining global surface smoothing, a substrate surface is smoothed by conducting chemical mechanical polishing in a plurality of separate steps using different types of slurry which are different in degree of dispersion of abrasive particles. For example, chemical mechanical polishing is first conducted by using non-suspension-type slurry, and chemical mechanical polishing is next conducted by using suspension-type slurry. By polishing a Cu film, for example, by using this chemical mechanical polishing, a plug is made in a via hole.