Effects of Ti addition on the morphology, interfacial reaction, and diffusion of Cu on SiO2

Abstract

In this work, thin films of pure Cu, and Cu with 0.02 or 2.98 wt % Ti were deposited on SiO2 covered Si substrates. The samples were annealed at 500–800 °C in vacuum to investigate their morphological evolution, interfacial reaction, and diffusion. X-ray diffraction reveals Cu(111) and Cu(200) peaks for pure Cu and Cu(0.02 wt % Ti) films. However, the Cu(2.98 wt % Ti) film exhibits a very weak Cu(200) peak, indicating that this film is textured in 〈111〉 orientation. Concurrently, scanning electron microscopy shows that the grain size of the Cu(2.98 wt % Ti) film is significantly smaller than those of pure Cu and Cu(0.02 wt % Ti) films. In addition, Cu(2.98 wt % Ti) film remains smooth after annealing up to 800 °C, while the other two films become discontinuous. X-ray photoelectron spectroscopy indicates that a TiOx layer has formed at the Cu(0.02 wt % Ti)/SiO2 and Cu(2.98 wt % Ti)/SiO2 interfaces after 700 °C annealing. Nevertheless, the TiOx layer is thicker in the Cu(2.98 wt % Ti) system than in the Cu(0.02 wt % Ti) system. Consequently, the Cu(2.98 wt % Ti) film shows no diffusion of Cu into SiO2 at temperatures up to 700 °C. Connections between the segregation of Ti addition and the morphological/interfacial characteristics are discussed.