Standardization of Specific Contact Resistivity Measurements using Transmission Line Model (TLM)

The transmission line model (TLM) method is most commonly used to determine the specific contact resistivity of metal -semiconductor contacts. Inconsistencies have been observed in the literature in reported values of specific contact resistivities in devices ranging in their dimensions, e.g between those in nm-μm scaled integrated circuit devices and mm-cm scaled photovoltaic devices indicating that the contact resistivity extraction may depend on dimensions. Therefore, TLM test geometries need to be specified. This paper discusses the effect of the TLM width on extracted transfer length. The effect of pad length is investigated using the Exact Field Solution model. Linear and circular TLM test structures were created and tested on Al, NiSi/Al on p+n and n+p substrates. Specific contact resistivitiy values agree in both wide linear and circular TLM methods. However, sheet resistance values differ.