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

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 TiO
2
seed and/or 2 nm Nb
2
O
5
cap layer in a bilayer (BL) and/or trilayer (TL) configuration with TiN top and bottom electrodes. We show how the Nb
2
O
5
cap is able to facilitate the transition from (anti-FE) tetragonal into (FE) orthorhombic phase by injecting oxygen in the HZO and find that the TiO
2
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 ~30μC/cm
²
at 1.8 MV/cm or devices with a record high 2P
R,max
of 66.5 μ C/cm
²
after 3× 10
⁶
cycles at 3 MV/cm.