Analytical and Finite-Element Modeling of a Two-Contact Circular Test Structure for Specific Contact Resistivity

The specific contact resistivity of a metal-semiconductor ohmic contact can be determined using a number of different test structures, and several of these use the transmission line model approach. In the circular transmission line model test structure, the concentric circular contacts have circular equipotentials in the semiconductor layer, and transmission line model equations can be used to describe their current-voltage behavior. Using test structures with two circular contacts of three different sizes, we present a new technique for determining specific contact resistivity. The analytical expressions are developed and presented, and finite-element modeling results are undertaken to demonstrate the accuracy of the technique. The scaling behavior of this test structure is also discussed. There are no error corrections required for determining contact parameters using the presented test structure.