Surface and interface studies of RF sputtered HfO2 thin films with working pressure and gas flow ratio

• Published in: Journal of materials science. Materials in electronics 2015-08, Vol.26 (8), p.6025-6031
• Main Authors: Das, K. C., Ghosh, S. P., Tripathy, N., Bose, G., Ashok, A., Pal, P., Kim, D. H., Lee, T. I., Myoung, J. M., Kar, J. P.
• Format: Article
• Language: English
• Subjects: Characterization and Evaluation of Materials; Chemistry and Materials Science; Materials Science; Optical and Electronic Materials
• ISSN: 0957-4522; 1573-482X
• DOI: 10.1007/s10854-015-3179-9

In this work, hafnium oxide (HfO 2 ) thin films were deposited on p-type silicon substrate by radio frequency magnetron sputtering at various working pressure ranging from 4 × 10 −3 to 1 × 10 −2 mbar and Ar/O 2 flow ratio from 1:4 to 4:1. The morphological and electrical properties of the sputtered films were investigated and a correlation between the surface and electrical properties of the HfO 2 films was established with the variation of sputtering parameters. The evolution of monoclinic structure of the hafnium oxide thin films was observed by XRD studies. The surface of the HfO 2 films became rough with the increase in grain size at the sputter pressure of 8 × 10 −3 mbar and Ar/O 2 gas flow ratio of 1:4. The formation of HfO 2 bond was seen from FTIR spectra. The oxide charge density has a lower value for the sputter pressure of 8 × 10 −3 mbar and Ar/O 2 gas flow ratio of 1:4 due to the evolution of larger grains. The interface charge density was found to be minimum at a sputter pressure of 8 × 10 −3  mbar.