Ferroelectric ZrO2 ultrathin films on silicon for metal-ferroelectric-semiconductor capacitors and transistors

Enhanced ferroelectric properties of nanoscale ZrO2 thin films by an HfO2 seed layer are demonstrated in metal-ferroelectric-semiconductor (Si) capacitors and transistors prepared with a low thermal budget of 400 degrees C. The seeding effect of the HfO2 layer leads to the enhancement of crystallization into the orthorhombic phase and the increase of remnant polarization of the sub-10 nm ZrO2/HfO2 bilayer structure. The ferroelectric field-effect transistor with the ZrO2/HfO2 bilayer gate stack reveals a large memory window of-1.2 V and a steep sub-threshold swing below 60 mV/decade. As compared with the Hf0.5Zr0.5O2 thin film, superior ferroelectric properties of the ZrO2/HfO2 bilayer structure show great potential for ferroelectric memory devices fabricated on Si substrates.

Automated summary

The ferroelectric properties of nanoscale ZrO2 thin films can be enhanced by adding an HfO2 seed layer in metal-ferroelectric-semiconductor structures. The ZrO2/HfO2 bilayer structure demonstrates improved crystallization and polarization effects, which make it suitable for ferroelectric memory devices fabricated on Si substrates.