Integration Of Ferroelectric Capacitors On Si Using Ti-Al Film As A Barrier Layer

Ti-Al film(10 nm),Ti-Al-N film(10 nm) have been deposited on the Si(001) substrates by magnetron sputtering method in various N2/Ar flow ratios. X-ray diffraction (XRD), scanning electron microscope(SEM) and four-point probe measurement (FFP) have been employed to characterize the barrier performance. It is found that the Ti-Al-N films remain amorphous after high temperature annealing up to 750 oC, no obvious reactions or interdiffusion occur in the Cu/Ti-Al-N/Si samples. and no Cu silicide is observed for the Cu/Ti-Al-N/Si sample compared to the Cu/Ti-Al/Si sample in which Cu3Si is observed. This indicates that dissolved nitrogen in Ti-Al can greatly reduce the Gibbs free energy of the barrier, enhance high temperature stability and increase the failure temperature. The Ti-Al-N film is ideal diffusion barrier for Cu metallization.The effect of amorphous Ti-Al buffer layer deposited by radio-frequency magnetron sputtering on the microstructural and physical properties of Ba0.6Sr0.4TiO3 (BST) film prepared by pulsed laser deposition technique on Pt/Ti/SiO2/Si(001) substrates was studied. It is found that the Ti-Al buffer layer can effectively prevent the interdiffusion between Pt electrode and BST film, lower the concentration of oxygen vacancy of the BST film, and improve the dielectric properties of the BST capacitors.La_0.5Sr_0.5CoO₃ (LSCO)/Pb(Zr_0.4Ti_0.6)O₃ (PZT)/La_0.5Sr_0.5CoO₃ (LSCO)/Ti-Al/Cu/Ti-Al/Si heterostructure has been fabricated via both sol-gel and magnetron sputtering methods using Ti-Al film as diffusion barrier layer and oxygen barrier layer. The ferroelectric properties have been measured by a ferroelectric tester. It is found that the LSCO/PZT/LSCO capacitor has very good saturated ferroelectric loop, and the remnant polarization and coercive voltage, measured at 5 V, are ²3.0μC/cm² and ¹.6 V, respectively.