Determining specific contact resistivity from contact end resistance measurements

A method is described to determine specific contact resistivity from contact end resistance measurements using a transmission line model. A test pattern is described which minimizes the effect of current fringing around contact corners and yields an accurate determination of contact width. With this pattern, the specific contact resistivities measured on 1.3 wt % Si/Al contacts to n+ silicon junctions with different dopings show very consistent values and are independent of contact geometries. The dependence of measured specific contact resistivities on doping concentration is also in good agreement with the predictions of tunneling theory. Surprisingly, the dependence on surface concentration extends well beyond the usual range of electrically active solid solubility.