Grain Size Engineering of Ferroelectric Zr-doped HfO2 for the Highly Scaled Devices Applications

Ferroelectric Zr-doped HfO2 (HZO) is a promising candidate component for the future transistors and memory devices applications. To address the device-to-device variation in those highly scaled devices, the grain properties of 12-nm-thick HZO films are investigated and optimized by altering the atomic layer deposition (ALD) cycle ratio of HfO2 and ZrO2 at a constant Zr concentration. The largest remanent polarization $2{P}_{r}$ of $41\mu \text{C}$ /cm(2), refined average grain radius from 16.6 nm to 13 nm, and improved grain size distribution with the standard deviation reduced from 5 to 3.3 are realized by adjusting the ALD cycle ratio to 5/5. Furthermore, the possible underlying mechanisms for the ferroelectric behaviors and the growth modes of the HZO films deposited with various cycle ratios are demonstrated.