The effect of lateral current spreading on the specific contact resistivity in D-resistor Kelvin devices

The effects of lateral current spreading on the determination of ohmic contact resistivity when Using Kelvin devices with a D-resistor layout are studied by numerical simulation and experimental measurements. Simulations show that the extracted contact resistivity can be higher or lower than the actual resistivity. The extracted contact resistivity is found to be a strong function of the geometrical layout, the semiconductor sheet resistance, and the actual contact resistivity. Futhermore, it is shown that the actual contact resistivity cannot be determined below some minimum value and the effect of misalignment during processing is shown to produce significant errors. Good agreement with the experiment is found for As-implanted ohmic contacts to Si. Guidelines for the design, processing, and evaluation of D-resistor Kelvin devices are presented.