Thermal stability of rare-earth based ultrathin Lu2O3 for high-k dielectrics
Lee, Pooi See
Lai, J. C.
Date of Issue2007
School of Materials Science and Engineering
Lu2O3 thin film was deposited on n-type (100) Si substrates using pulsed laser deposition. A k value of 15.95 with an equivalent oxide thickness (EOT) of 1.10 nm and a current density of 2.6×10−5 A/cm2 at +1 V accumulation bias is achievable for the 4.5 nm thick Lu2O3 thin film deposited at room temperature after postdeposition annealing at 600 °C in oxygen ambient. Annealing a similar sample at 900 °C caused the EOT and leakage current density to increase to 1.68 nm and 1×10−4 A/cm2, respectively. High resolution transmission electron microscopy analysis has shown that Lu2O3 film remains amorphous at high temperature annealing at 900 °C. An x-ray reflectivity analysis on a separately prepared sample with lower annealing temperature (800 °C) suggested a formation of Lu-based silicate layer. It is believed that the formation of low-k silicate layer may have contributed to the observed increase in EOT and the reduction in the k value.
Journal of vacuum science & technology B
© 2007 American Vacuum Society. This paper was published in Journal of Vacuum Science & Technology B and is made available as an electronic reprint (preprint) with permission of American Vacuum Society. The paper can be found at DOI: [http://dx.doi.org/10.1116/1.2749526]. One print or electronic copy may be made for personal use only. Systematic or multiple reproduction, distribution to multiple locations via electronic or other means, duplication of any material in this paper for a fee or for commercial purposes, or modification of the content of the paper is prohibited and is subject to penalties under law.