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Formation of Ge Nanocrystals in Lu2O3 High-k Dielectric and its Application in Non-Volatile Memory Device

  • Mei Yin Chan (a1), Pooi See Lee (a1) and Vincent Ho (a1)

A simple technique for the formation of Ge nanocrystals embedded in amorphous Lu2O3 high-k dielectric was demonstrated by pulsed laser ablation followed by rapid thermal annealing in N2 ambient. The structure and composition of the Ge nanocrystals in the oxide matrix have been studied by transmission electron microscopy (TEM) and x-ray photoelectron spectroscopy (XPS) analysis. A significant change in the structure and chemical composition of the film was obtained upon annealing. Cross-sectional and plan-view TEM images confirmed the formation of small Ge nanocrystals in amorphous Lu2O3 matrix with a mean size of about 6nm in diameter and a high areal density of 7 × 1011cm−2. The nanocrystals are well-isolated by the amorphous Lu2O3 in between, with almost spherical shape which are favorable for non-volatile memory (NVM) application due to an effective charge confinement. XPS measurements on the as-deposited sample indicate the existence of Ge in its oxidized state, consisting of GeO2 and Ge suboxides. A spontaneous reduction of GeO2 and GeOx was obtained after the annealing treatment, which provides Ge nuclei for nanocrystal formation. It is found that a low annealing temperature of 400oC is sufficient to dissociate the GeO2 and GeOx leading to the formation of Ge nanocrystals. The application of the nanocrystals in NVM devices was demonstrated by C-V characterization of the memory capacitor devices fabricated with Al2O3 control oxide layer. C-V results show a significant effect of the structure and composition of the film on the electrical performance of the device. The annealed device exhibits good memory behavior with a large memory window of 1.2V achieved with a low operation voltage.

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1.Fernandes, A. et. al., IEDM Tech Dig., 155 (2001).
2.Saitoh, M. et. al., IEDM Tech Dig., 181 (2002).
3.Lee, J. J., Wang, X., Bai, W., Lu, N., Liu, J. and Kwong, D. L., Symp. VLSI Tech. Dig., 33 (2003)
4.Kim, D. W., Kim, T. and Banerjee, S. K., IEEE Trans. Electron Devices 50, 1823 (2003).
5.Kim, D. W., Prins, F. E., Kim, T., Hwang, S., Lee, C. H., Kwong, D. L. and Banarjee, S. K, IEEE Trans. Electron Devices 50, 510 (2003).
6.Wan, Q., Zhang, N. L., Liu, W. L., Lin, C. L. and Wang, T. H., App. Phys. Lett. 83, 138 (2003)
7.Lee, P. F., Lu, X. B., Dai, J. Y., Chan, H. L. W., Jelenkovic, e., and Tong, K. Y., Nanotechnology 17, 1202 (2006)
8.Wang, Y. Q., Chen, J. H., Yoo, W. J., Yeo, Y. C., Lim, S. J., Kwong, D. L., Du, A. Y., and Balasubramanian, N., Appl. Phys. Lett. 84, 5407 (2004)
9.Lu, X. B., Lee, P. F., and Dai, J. Y., App. Phys. Lett. 86, 20311 (2005)
10.Yuan, C. L., Darmawan, P., Setiawan, Y. and Lee, P. S., Europhys. Lett. 74, 177 (2006)
11.Scarel, G., Bonera, E., Wiemer, C., Tallarida, G., Spiga, S. and Fanciulli, M., Appl. Phys. Lett. 85 630 (2004).
12.Ohmi, S., Takeda, M., Ishiwara, H., and Iwai, H., J. Electrochem. Soc. 151, G279 (2004).
13.Schlom, D. G. and Haeni, J. H., MRS Bull. 27, 198 (2002).
14.Marsella, L. and Fiorentini, V., Phys. Rev. B 69, 172103 (2004).
15.Darmawan, P., Yuan, C. L. and Lee, P. S., Solid-State Comm., 1 (2006).
16.Winkler, O., Merget, F., Heuser, M., Hadam, B., Baus, M., Spangenberg, B. and Kurz, H., Microelectron. Eng. 61, 497 (2002)
17.Usuki, T., Futatsugi, T. and Yokoyama, N., Microelectron.Eng., 47, 281 (1999)
18.Hanafi, H. I., Tiwari, S. and Khan, I., IEEE Trans. Electron Devices 43, 1553 (1996)
19.CRC Handbook of Chemistry and Physics, 84th ed. Edited by Lide, D. R. (CRC, Boca Raton, FL, 2003).
20.Fujii, M., Hayashi, S. and Yammamoto, K., Jpn. J. Appl. Pjys. Part 1 30, 687 (1991)
21.Wang, Y. Q., Chen, J. H., Yoo, W. J., Yeo, Y. C., Lim, S. J., Kwong, D. L., Du, A. Y., and Balasubramanian, N., Appl. Phys. Lett. 84, 5407 (2004)
22.Dutta, A. K., Appl. Phys. Lett. 68, 1189 (1996)
23.Paine, D. C., Caragianins, C., Kim, T. Y., Shigesato, T., and Ishikawa, T., Appl. Phys. Lett. 62, 2482 (1993)
24.Shi, Y. et. al., J. Appl. Phys. 84, 2358 (1998)
25.Kanjilal, A. st. al., Appl. Phys. Lett. 82, 1212 (2003)
26.Kouvatsos, D. N. et. al., Appl. Phys. Lett. 82, 297 (2003)
27.Sargentis, Ch. et. al., Appl. Phys. Lett. 88, 073106 (2006)
28.Normand, P. et. al., Appl. Phys. Lett. 83, 168 (2003)
29.Tseng, J. Y. et. al., Appl. Phys. Lett. 85, 2595 (2004)
30.Liss, B. et. al., J. Appl. Phys. 78, 1824 (2005)
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