Flash-lamp annealing of ternary rare earth oxides for use as alternative high-k materials

Motivated by the fact, that millisecond annealing methods are going to play an important role in an advanced CMOS technology, this investigation of the effects of flash-lamp annealing (FLA) on actual and possible future high-k materials was performed [1]. Employed high-k materials were HfO2, LaYbO3, LaScO3 or LaLuO3.
HfO2 is already used in the industry while LaYbO3, LaScO3 and LaLuO3 are interesting as possible replacements, because of their thermally stable (>800°C) amorphous states with k-values above 20 as well as large bandgaps > 5 eV [2, 3, 4].
The high-k materials were deposited on p-Si by atomic-layer, molecular beam or pulsed laser deposition. Afterwards, FLA was used as a post-deposition annealing technique in which the pulse durations and peak temperatures were varied from 1 to 20 ms and 1000 to 1300°C, respectively. Pt-top and Al-back contacts were created for electrical measurements.
The microstructure of the samples was investigated by electron microscopy, XRD and nuclear methods (RBS, ERD), while the electrical properties were derived from current-voltage and capacitance-voltage measurements. It was found that for example metal-oxide semiconductor capacitors (MOSCAP) containing LaLuO3 can profit from FLA because this oxide remains amorphous and the capacitance is increased. On the other hand, the picture is not so clear for HfO2-MOSCAPs, because their capacitance is reduced and the oxide crystallizes while the leakage current is decreased.

References:

[1] J. C. Gelpey, S. McCoy, D. Camm and W. Lerch, Mater. Sci. Forum 573-574, 257 (2008)
[2] W. Su, L. Yang, B. Li, Appl. Surf. Sci. 257, 2526 (2011)
[3] V. V. Afanas’ev, A. Stesmans, C. Zhao, M. Caymax, T. Heeg, J. Schubert, Y. Jia, D. G. Schlom, and G. Lucovsky, Appl. Phys. Lett. 85, 5917 (2004)
[4] J. Lehmann, N. Shevchenko, A. Mücklich, J.v. Borany, W. Skorupa, J. Schubert, J.M.J. Lopez, S. Mantl, Microelectron. Eng. 88, 1346 (2011)