Semiconductor device having a substrate covered with a high impurity concentration first polycrystalline layer and then a lower impurity concentration second polycrystalline layer

摘要

A semiconductor device has a semiconductor substrate of a first conductivity type, and a diffused region of a second conductivity type. A first insulation film is formed on the substrate, having an opening exposing the surface of the diffused region. First and second polycrystalline layers doped with impurities associated with the second conductivity type are disposed in the opening, and the concentration of the impurities of the first polycrystalline layer is higher than that of the second polycrystalline layer. A metal electrode is formed on the second polycrystalline layer.