Ferroelectricity Enhancement in Hf0.5Zr0.5O2 Capacitors by Incorporating Ta2O5 Dielectric Seed Layers

Abstract

Recently, dielectric/ferroelectric (DE/FE) bilayer systems have been extensively investigated for achieving high remanent polarization in Hf0.5Zr0.5O2 (HZO) based MFM capacitors. Herein, we report significant enhancement in the ferroelectric property of HZO capacitors by incorporating Ta2O5 as the dielectric seed layer. Thickness of the Ta2O5 layer was incorporated at both top and bottom of the HZO films and the thickness of the seed layer was varied from 10 to 50 angstrom. When the Ta2O5 dielectric films were inserted at the top, the highest remanent polarization similar to 16.83 mu C/cm(2) was observed in case of 20 A films as compared to that of similar to 13.21 mu C/cm(2) of the reference HZO device. Similarly, for bottom Ta2O5 dielectric films, the highest remanent polarization similar to 15.24 mu C/cm(2) was observed in case of 20 angstrom films. When we compared both the stacks, the best result was observed in case of top Ta2O5. The coercive field (E-c) was also found to be nearly same with the HZO based device despite the incorporation of the dielectric layer. The enhanced ferroelectricity of these devices can be used in memory devices, FeFETs, FTJ and sensors applications.