Enhanced physical and electrical properties of HfO2 deposited by atomic layer deposition using a novel precursor with improved thermal stability

With the increased application range of Hf-based oxides in memory devices, such as high-k capacitors, gate dielectrics, and ferroelectric devices, improvement in the properties of HfO2 thin films have been received considerable attention. To achieve improved properties HfO2 thin films deposited by atomic layer deposition (ALD), one strategic way is to develop a process incorporating a new precursor with improved thermal stability. In this paper, HfO2 thin films were deposited by ALD process using a novel precursor modified with a cyclopentadienyl-based ligand to improve thermal stability, and the improved properties were investigated. The ALD process window has been extended to higher temperatures. In addition, with increases in deposition temperature, the impurity concentration, surface roughness, density, and crystallinity of HfO2 were improved. Finally, the HfO2 thin film deposited at a high temperature significantly reduced the leakage current (from 5.2 x 10- 7 A/cm2 to 3.1 x 10-9 A/cm2 measured at 0.7 V) without a significant change in dielectric constant, and the remanent polarization characters were also observed. Therefore, we suggest that HfO2 deposited using the proposed hafnium precursor can be applied as a key high-k component in next-generation memory devices and ferroelectric-based semiconductor devices.