Abstract: A semiconductor structure and methods for forming the same. A semiconductor fabrication method includes steps of providing a structure. A structure includes (a) a dielectric layer, (b) a first electrically conductive region buried in the dielectric layer, wherein the first electrically conductive region comprises a first electrically conductive material, and (c) a second electrically conductive region buried in the dielectric layer, wherein the second electrically conductive region comprises a second electrically conductive material being different from the first electrically conductive material. The method further includes the steps of creating a first hole and a second hole in the dielectric layer resulting in the first and second electrically conductive regions being exposed to a surrounding ambient through the first and second holes, respectively. Then, the method further includes the steps of introducing a basic solvent to bottom walls and side walls of the first and second holes.