High performance La-doped HZO based ferroelectric capacitors by interfacial engineering

Abstract

We show how interfacial oxide engineering in La-doped hafnium zirconate (HZO) ferroelectric (FE) capacitor stacks can be used to significantly improve the ferroelectric response and remnant polarization (P-R) of the HZO. This is achieved by incorporating either a 1 nm TiO2 seed and/or 2 nm Nb2O5 cap layer in a bilayer (BL) and/or trilayer (TL) configuration with TiN top and bottom electrodes. We show how the Nb2O5 cap is able to facilitate the transition from (antiFE) tetragonal into (FE) orthorhombic phase by injecting oxygen in the HZO and find that the TiO2 seed layer favorably improves the grain orientation inside the HZO, resulting in a higher 2P(R) and reduced wake-up. Finally, depending on the precursors of Hf and Zr that are used, we demonstrate both trilayer devices with an endurance of up to 10(11) cycles with a final 2P(R) of similar to 30 mu C/cm(2) at 1.8 MV/cm or devices with a record high 2P(R, max) of 66.5 mu C/cm(2) after 3x10(6) cycles at 3 MV/cm.