Hostname: page-component-78c5997874-m6dg7 Total loading time: 0 Render date: 2024-11-10T15:13:33.906Z Has data issue: false hasContentIssue false
  • English
  • Français

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

Published online by Cambridge University Press:  01 February 2011

Mei Yin Chan ,
Pooi See Lee  and
Vincent Ho
Mei Yin Chan
Affiliation:
mychan@pmail.ntu.edu.sg, Nanyang Tehcnological University, School of Materials Science and Engineering, Block N4.1, Nanyang Avenue, Singapore, 639798, Singapore, (+65)93630478, (+65)67909081
Pooi See Lee
Affiliation:
mychan@pmail.ntu.edu.sg, Nanyang Tehcnological University, School of Materials Science and Engineering, Block N4.1, Nanyang Avenue, Singapore, 639798, Singapore, (+65)93630478, (+65)67909081
Vincent Ho
Affiliation:
mychan@pmail.ntu.edu.sg, Nanyang Tehcnological University, School of Materials Science and Engineering, Block N4.1, Nanyang Avenue, Singapore, 639798, Singapore, (+65)93630478, (+65)67909081
Get access

Abstract

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.

Keywords

nanostructurememorydielectric
Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 997: Symposium I – Materials and Processes for Nonvolatile Memories II , 2007 , 0997-I02-02
Copyright
Copyright © Materials Research Society 2007

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

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