We study the performance and reliability of carbon nanofiber (CNF) interconnects under high-current stress by examining CNF breakdown for four test configurations, suspended/supported with/without tungsten deposition. The use of W is to improve the CNF-electrode contact. The supported cases show a larger current density just before breakdown than the suspended ones, suggesting an effective heat dissipation to the substrate. The W-deposited contacts reduce the initial total resistance from megaohm range without W to kilo-ohms. High-current stress does not change the total resistance of the test structures with W unlike those without W deposition.

Current-induced breakdown is investigated for carbon nanofibers (CNF) for potential interconnect applications. The measured maximum current density in the suspended CNF is inversely proportional to the nanofiber length and is independent of diameter. This relationship can be described with a heat transport model that takes into account Joule heating and heat diffusion along the CNF, assuming that breakdown occurs when and where the temperature reaches a threshold or critical value.

Carbon nanofibers (CNF) are proposed for electrical interconnect applications because of their relatively large current capacity and ability to form well-aligned one-dimensional structures. It is experimentally determined that nanofibers that are suspended between two electrodes breakdown at or near the nanofiber center. Based on published property values a simple model is used to calculate the temperature and quantify the effect of heat generation at the CNF/electrode interface on the nanofiber temperature. The model has the capability to separately account for the substrate temperature and the temperature at the CNF/electrode junction. It is determined that the CNF reaches a temperature at which carbon oxidation is likely to occur.

Monte Carlo simulation of scanning electron microscopy bright contrast images of suspended carbon nanofibers Appl. Phys. Lett. 90, 083111 (2007); 10.1063/1.2450655Bright contrast imaging of carbon nanofiber-substrate interface Electron field emission from room temperature grown carbon nanofibersThe authors present scanning transmission electron microscopy ͑STEM͒ of carbon nanofibers ͑CNFs͒ on a bulk substrate using conventional scanning electron microscopy ͑SEM͒ without specimen thinning. By utilizing the electron beam tilted Ͼ85°from the substrate normal, bright-field STEM contrast is obtained for the CNFs on substrate with conventional SEM. Analysis of the observed contrast using Monte Carlo simulation shows that the weakly scattered electrons transmitted from the CNF are selectively enhanced by the largely tilted substrate and result in the observed STEM contrast. This mechanism provides a useful STEM imaging technique to investigate the internal structure of materials on bulk substrates without destructive specimen thinning.

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