Carbon nanotube (CNT) vias were fabricated at 500 °C with different widths and lengths. The electrical resistance of the CNT vias was measured using four-point probe structures at temperatures between 25 °C and 190 °C. It was found that the temperature coefficient of resistance (TCR) of the CNT vias changes with both length and width. Most of the vias displayed a negative TCR between -300 and -400 ppm/K, against 3900 ppm/K for Cu, but for wider and shorter vias, this value becomes positive. A simple model is introduced, which can explain the length-dependent behavior.