Demonstration of High Ferroelectricity (P-r similar to 29 mu C/cm(2)) in Zr Rich HfxZr1-xO2 Films

Abstract

In this letter, we report excellent ferroelectricity with high remanent polarization (P-r) in Zr rich hafnium zirconium oxide (HZO) films using high pressure postmetallization annealing (HPPMA). HZO films annealed using rapid thermal annealing (RTA) show highest ferroelectricity when the Hf:Zr ratio is 1:1 and exhibit antiferroelectricproperty for Zr rich films. However, under HPPMA, Zr rich films demonstrate enhanced ferroelectric property as compared to 1:1 HZO films and the best result was observed for 1:3 HZO films. The HZO (1:3) films by HPPMA show P-r as high as similar to 29 mu C/cm(2), which is almost 50% higher than that achieved for the best condition of RTA (P-r similar to 19 mu C/cm(2)). Besides, due to the presence of high Zr, the HZO (1: 3) films by HPPMA exhibit considerably higher dielectric constant (k similar to 43) and low coercive field (E-c similar to 1.21 MV/cm) as compared to that of HZO (1:1) films by RTA (k similar to 37, E-c similar to 1.35 MV/cm). We believe the enhanced ferroelectricity in Zr rich HZO films can be due to more o/t-phase formation in ZrO2 under HPPMA as compared to that of RTA. On the other hand, more m-phase formation was observed in HfO2 under HPPMA, resulting in a significant drop of Pr in case of Hf rich HZO. The demonstration of enhanced ferroelectric properties by Zr rich HZO films can be helpful for high functional semiconductor device applications.