Carbon nanotube vertical interconnects fabricated at temperatures as low as 350 °C

Carbon nanotube (CNT) vertical interconnects (vias) were fabricated on conductive substrates at a record-low temperature of 350 degrees C, using only standard semiconductor manufacturing techniques and materials. CNT growth rates were investigated for both Co and a Co-Al alloy catalysts, and compared to that of Fe. The activation energy of the Co-based catalysts was found to be lower, allowing lower temperature growth. Using Co as catalyst full-wafer CNT test vias were fabricated at 350 degrees C, and 400 degrees C, and electrically characterized. Good uniformity was obtained, with no apparent yield-loss compared to higher temperature fabricated CNT vias. A negative thermal coefficient of resistance was observed of -800 ppm/K, which is advantageous for interconnect applications. The resistivity of the vias increases with temperature, up to 139 m Omega cm for 350 degrees C, but was found to be lower than several values obtained from literature of CNT vias fabricated at higher temperatures. (C) 2014 Elsevier Ltd. All rights reserved.