A method of manufacturing a semiconductor device includes forming a diffusion barrier layer on a substrate, and forming at least two features on the substrate such that the diffusion barrier layer is respectively disposed between each feature and the substrate and contacts the at least two features. A first impurity region of the substrate contains impurities of a first type, a second impurity region of the substrate contains impurities of a second type, different from the first type, a first feature of the at least two features is in the first impurity region, and a second feature of the at least two features is in the second impurity region, such that the second feature is electrically isolated from first feature by the different impurity regions.