Semiconductor device having an improved low resistive contact

A semiconductor device having a metal semiconductor contact structure comprising:

• a semiconductor substrate of one conductive type;
• a first semiconductor region of opposite conductive type formed on said substrate, said first semiconductor region comprising a buried layer formed on said semiconductor substrate and an epitaxial layer formed on said buried layer, said buried layer having a higher dopant concentration than a dopant concentration of said epitaxial layer;
• a second semiconductor region of said one conductive type in contact with said first semiconductor region;
• a third semiconductor region of said opposite conductive type in contact with said second semiconductor region;
• a metal region formed in said first semiconductor region, said metal region being of sufficient conductivity to serve as a contact plug, said metal region comprising a bottom surface within said buried layer;
• a semiconductor film having a wider band gap than a band gap of said first semiconductor region, said semiconductor film being in contact at its opposite surfaces with a part of said metal region and a part of said first semiconductor region, said semiconductor film being sufficiently doped with dopant of said one conductive type to suppress an electrical current flow of carriers between said part of said metal region and said part of said first semiconductor region through said semiconductor film, said semiconductor film covering opposite side portions of said metal layer without lowering a top and bottom surface of said metal layer.