Growth mechanism of HfO2 film on H-terminated Si (100) surface from atomic layer deposition process using tetrakis(ethylmethylamino)hafnium

Abstract

The deposition of HfO2 on H-terminated Si (100) surfaces presents both interest and challenges due to the complexity of the surface reaction mechanisms. Previous experimental studies reported conflicting results regarding the formation of interfacial layers and the presence of incubation periods during the initial cycles of the HfO2 atomic layer deposition (ALD) process. In this study, we provide a detailed analysis of the surface reaction mechanism of HfO2 ALD on H-terminated Si (100) surfaces using tetrakis(ethylmethylamino)hafnium (TEMAH) and water. Our findings demonstrate that TEMAH chemisorbs onto the H-terminated Si (100) surface through the formation of two N-Si interfacial bonds. Additionally, the remaining ligands of the adsorbed Hf precursor are efficiently removed through hydroxylation during the water pulse, with low energy barriers of +25.9 to +30.0 kJ/mol. Furthermore, the N-Si interfacial bonds can be broken, allowing for the formation of Hf-O-Si interfacial bonds during either the water pulse or post-deposition processes. This work provides valuable insights into the surface reactions of HfO2 ALD and explains the varied interfacial bonding and incubation periods observed in prior studies.