Circular Cross Kelvin Resistor test structure for low specific contact resistivity

Abstract

In determining the specific contact resistance of an Ohmic contact, using conventional Cross Kelvin Resistor (CKR) test structures, the errors in doing so occur from parasitic resistances around the contact. These parasitic resistances are difficult to determine because no convenient analytical expression is available to calculate this resistance. However, electrical current entering a circular contact uniformly from all directions can be modeled using analytical expressions. Here we present a new test structure where parasitic resistance can easily be calculated because it occurs between concentric equipotentials. This resistance is then subtracted from the total resistance to give the resistance due to the contact interface and hence the specific contact resistance of that interface. Using aspects of the CKR and the Circular Transmission Line Model (CTLM) we have designed a new test structure, here called the Circular Cross Kelvin Resistor (CCKR) test structure for determining specific contact resistance.