Measuring electrical interfacial resistance of metal using modified transfer length method

Abstract

With advances in device miniaturization, the electrical interfacial resistance (EIR) between contacting metals has become a critical factor governing the electrical and thermal performance of high-density electronic and display systems. However, accurate quantification of the EIR remains challenging because of its relatively small magnitude and strong dependence on process-induced interfacial characteristics. In this study, an EIR measurement methodology based on a modified transfer length method (TLM) and a metallic bilayer structure (MBS) is proposed, enabling the realistic replication of thin-film metal–metal interfaces formed during device fabrication. By developing an analytical model that integrates the resistance of the two contacting metals with a spatially distributed current transfer across the contact area, the EIR can be extracted as a function of the contact length. The model was validated through finite element simulations, which demonstrated excellent agreement over a wide range of normalized contact lengths. Additionally, the critical contact length required for reliable EIR measurements was determined. Experimentally, MBS was fabricated using a lift-off process, and the EIR was measured using a four-wire method. The extracted contact resistivity was on the order of 10−10 Ω·m2. The proposed approach provides a robust and quantitative framework for evaluating the EIR in realistic metal–metal interfaces, offering a practical utility and scalable framework for the design and optimization of next-generation microelectronic and display devices.