Investigation of Carbon Nanotube Growth on Multimetal Layers for Advanced Interconnect Applications in Microelectronic Devices

Abstract

In this paper we present the microstructural study behind the growth of carbon nanotubes (CNTs) on the multimetal buffer layers due to its importance in microelectronics and microelectromechanical systems applications. Two different buffer layers, i.e., aluminum (Al) and titanium nitride (TiN), were deposited on the conductive layers of tantalum/copper/tantalum. A thick iron film was used as a catalyst layer to grow the CNTs. The fundamental mechanism behind the formation of catalyst nanoparticles on these two buffer layers, i.e., Al and TiN, was studied and analyzed by various characterization tools, such as atomic force microscopy, X-ray photoelectron spectroscopy, and scanning electron microscope. The formation of aluminum oxide nanoparticles during the CNT growth process was observed in the case of aluminum buffer layer. From the experimental results, it was concluded that TiN can be used as a stable buffer layer on the conductive metal lines. The CNTs growth on both buffer layers was found to be in random directions, which is due to the formation of bigger and less dense catalyst nanoparticles in comparison with the CNTs grown on the conventional buffer layer of thermally grown silicon dioxide on the silicon substrate, on which vertically aligned CNTs are grown.