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 500-800degreesC in vacuum to investigate their morphological evolution, interfacial reaction, and diffusion. X-ray diffraction reveals Cu(III) 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 electronx 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 800degreesC, 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 700degreesC 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 700degreesC. Connections between the segregation of Ti addition and the morphological/interfacial characteristics are discussed.