Surface and interface studies of RF sputtered HfO sub(2) 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, TI, Myoung, J M, Kar, J P
• Format: Article
• Language: English
• Subjects: Charge density; Electrical properties; Evolution; Gas flow; Hafnium oxide; Magnetron sputtering; Radio frequencies; Thin films
• ISSN: 0957-4522; 1573-482X
• DOI: 10.1007/s10854-015-3179-9

In this work, hafnium oxide (HfO sub(2)) thin films were deposited on p-type silicon substrate by radio frequency magnetron sputtering at various working pressure ranging from 4 10 super(-3) to 1 10 super(-2) mbar and Ar/O sub(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 sub(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 sub(2) films became rough with the increase in grain size at the sputter pressure of 8 10 super(-3) mbar and Ar/O sub(2) gas flow ratio of 1:4. The formation of HfO sub(2) bond was seen from FTIR spectra. The oxide charge density has a lower value for the sputter pressure of 8 10 super(-3) mbar and Ar/O sub(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 super(-3) mbar.