Evaluation of Cu(Ti) and Cu(Zr) alloys in barrier-less Cu metallization

Abstract

The thermal properties of Cu(Ti)/SiO2 and Cu(Zr)/SiO2 systems have been investigated to evaluate the potential application for Cu metallization. Cu(Ti) and Cu(Zr) alloy films were directly deposited on SiO2/Si substrates and subsequently annealed in vacuum at various temperatures of 300°C–700 °C for 1 h. The microstructure, interface characteristics, and electrical properties of both samples were measured using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), transmission electron microscope (TEM) and leakage currents detector. Results suggest that Cu alloy films have strong Cu(111) texture after the addition of a small amount of Zr or Ti．The sharp decline of Cu and Si concentrations at the interface suggest that both Ti and Zr addition can prevent the inter-diffusion between Cu and substrate. The leakage current densities of Cu(Zr) and Cu(Ti) show that Zr is more stable element to self-forming diffusion layer for advanced Cu interconnects.