Accurate Measurements of Small Resistances in Vertical Interconnects with Small Aspect Ratios

Resistance measurements of vertical interconnect elements by cross-bridge Kelvin resistors can yield values far below the expected value, if that resistance is calculated with the simple formula based on resistivity, interconnect length, and cross-sectional area; for small resistors, the measured value can even become negative. Analysis of current and potential distributions inside the simulated structures helps both to understand the causes of these non-realistic resistance values and to improve the design of the CBKR structures for preventing underestimation of the vertical interconnect resistance.