High performance of CNT-interconnects by the multi-layer structure

•Comparing the performance of CNT-interconnects with four combinations.•Improving the electrical properties and reliabilities by double layer structures.•Demonstrating the size and structure percolative conductance of CNT-interconnects.•Proposing further work for the CNT-interconnect optimization.

In this work, we propose two carbon nanotube (CNT) network fabrication processes, the normal spin rate coating (NR) and the slow spin rate coating (SR), and two interconnect structures, the single layer structure (SL) and the double layer structure (DL), to construct CNT-interconnects. We demonstrate and compare the performance of the CNT-interconnects with four kinds of process combinations: NR/SL, NR/DL, SR/SL and SR/DL. Generally, in the midst of these four combinations, the DL samples have higher conductive probabilities and less conductance variations, while SL/SR samples have the higher average conductance under the same amount of the CNT solution for CNT network formation. In addition, the phase transition phenomena occurred in the size dependent average conductance of CNT-interconnects are characterized and investigated by percolation theory. With the elongation of CNT-interconnects, the relationships between the average conductance and the square number would shift from linear region, power region to percolation region. Moreover, the results show that the resistance from the additional layer of Al2O3 in the double layer interconnect structure would influence the phase transition in the conductance of CNT-interconnects as well.