An interconnecting structure production method includes providing a substrate, forming a semiconductor layer on the substrate, forming a doped semiconductor layer on the semiconductor layer, the doped semiconductor layer containing a dopant, forming an oxide layer in a surface of the doped semiconductor layer by heating the surface of the doped semiconductor layer in atmosphere of an oxidizing gas with a water molecule contained therein, forming an alloy layer on the oxide layer, and forming an interconnecting layer on the alloy layer.