Atomic layer deposition (ALD) of HfO2 is a key technology for the application of high dielectric constant gate dielectrics ranging from conventional Si devices to novel nanodevices. The effects of the precursor on the growth characteristics and film properties of ALD HfO2 were investigated by using hafnium tetrachloride (HfCl4) and bis(ethylcyclopentadienyl)hafnium dichloride (Hf(EtCp)2Cl2, Hf(C2H5C5H4)2Cl2) with O2 plasma reactant. The growth characteristics were significantly affected even by simply changing the precursor. Theoretical calculations utilizing geometrical information on the precursor and density functional theory revealed that the steric demands of the precursor ligands have a dominant effect on the different growth characteristics rather than the reaction probability of the precursor on the surface. The chemical compositional analysis results showed that the Cl residue in the HfO2 films was reduced by using Hf(EtCp)2Cl2 due to the lower number of Cl atoms in each Hf precursor molecule and the relieved bridge formation of Hf-Cl-Hf bridge on the surface compared to HfCl4. The electrical property measurement results showed significantly improved insulating properties in HfO2 using Hf(EtCp)2Cl2 compared to HfCl4 due to the low concentration of Cl residue in the film. These results provide broad insights to researchers who are interested in the fabrication of high quality dielectric layers to achieve better device performance and overcome physical limitations in the nanoscale regime.
Bibliographical noteFunding Information:
ACKNOWLEDGMENTS: This work was supported by the Industrial Strategic Technology Development Program (10041926, Development of high density plasma technologies for thin film deposition of nanoscale semiconductor and flexible display processing) funded by the Ministry of Knowledge Economy (MKE, Korea), Korea Evaluation Institute of Industrial Technology (KEIT) funded by the Ministry of Trade, Industry and Energy (MOTIE) (Project No. 10050296, Large scale (Over 8) synthesis and evaluation technology of 2-dimensional chalcogenides for next generation electronic devices), the National Research Foundation of Korea (NRF) grant funded by the Korea government (MSIP) (No. NRF- 2014R1A2A1A11052588), the Center for Integrated Smart Sensors funded by the Ministry of Science, ICT & Future Planning as Global Frontier Project. (CISS-2011-0031848), Global PH.D Fellowship Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education (2014021146) and Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Science, ICT and future Planning (NRF-2014R1A2A1A11050893).
All Science Journal Classification (ASJC) codes
- Electronic, Optical and Magnetic Materials
- Physical and Theoretical Chemistry
- Surfaces, Coatings and Films