4.0-nm-thick amorphous Nb–Ni film as a conducting diffusion barrier layer for integrating ferroelectric capacitor on Si

• 4-nm-thick amorphous Nb–Ni film is first used as the conducting barrier layer.
• No obvious interdiffusion/reaction can be found from the LSCO/PZT/LSCO/Nb–Ni/Si.
• The LSCO/PZT/LSCO capacitor, measured at 5 V, possesses very good properties.
• Ultrathin amorphous Nb–Ni film is ideal to fabricate silicon-based FRAM.

We have successfully integrated La0.5Sr0.5CoO3/PbZr0.4Ti0.6O3/La0.5Sr0.5CoO3 (LSCO/PZT/LSCO) capacitors on silicon substrate using a ∼4.0-nm-thick amorphous Nb–Ni film as the conducting diffusion barrier layer. Transmission electron microscopy technique confirms that the Nb–Ni film is still amorphous after fabrication of the capacitors, and the interfaces related to Nb–Ni are clean and sharp without any findable interdiffusion/reaction. The LSCO/PZT/LSCO capacitor, measured at 5 V, possesses very good properties, such as large remanent polarization of ∼22.1 μC/cm2, small coercive voltage of ∼1.27 V, good fatigue-resistance, and small pulse width dependence, implying that ultrathin amorphous Nb–Ni film is ideal as the conducting diffusion barrier layer to fabricate high-density silicon-based ferroelectric random access memories.