between the first and second metal layers the undercut step of fig6 may be skipped resulting in the structure of fig4 after oxidation the structure of fig7 is preferred because of the vertical rectilinear current flow path afforded thereby from metal layer 6 to metal layer 10 in the finished structure a third metal layer 44 fig5 and 8 is then deposited and extends horizontally at 46 along the top of insulating layer 12 and vertically at 48 along the vertical side 18 of the layers over and between the first and second oxidation layers 32 and 34 in fig8 the third metal layer has a portion 50 extending horizontally inwardly into undercut 28 between horizontal first and second oxidation layer extensions 36 and 40 in fig8 the momom current flow path is vertically rectilinear through metal layer 6 oxidation layer extension 36 metallization extension 50 oxidation layer extension 40 and metal layer 10 in fig5 the path is through metal layer 6 oxidation layer 32 metallization portion 48 oxidation layer 34 and metal layer 10 it is thus seen that the m o m o m current flow path is through metal layer 6 oxidation layer 32 metallization 44 oxidation layer 34 metal layer 10 the structural geometry and processing steps of the invention enable different material and thicknesses to be used for metal layers 6 and 10 which in turn can selectively provide differing work functions for barrier heights different oxidation growth rates and differing junction areas if desired in a desirable aspect of the preferred embodiment in fig8 differing materials and thicknesses may be used for metal layers 6 and 10 to afford differing work function barrier.