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Ultra-Thin PZT Films for Low-Voltage Ferroelectric Non-Volatile Memories

Published online by Cambridge University Press:  10 February 2011

D.J. Wouters
Affiliation:
IMEC, Kapeldreef 75, B-3001 Leuven, Belgium, wouters@imec.be
G.J. Norga
Affiliation:
IMEC, Kapeldreef 75, B-3001 Leuven, Belgium
H.E. Maes
Affiliation:
IMEC, Kapeldreef 75, B-3001 Leuven, Belgium
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Abstract

For the possible application of PZT thin films in ferroelectric non-volatile memories, the potential of low-voltage switching is a major requirement. By straightforward thickness scaling down to 75nm, operation voltage can be reduced to 1.5V without degradation of the hysteresis properties. However, interface effects increase the coercive field for thinner films, so that operation voltage does not scale linearly with thickness. In view of the large difference in coercive field between bulk and thin-films, on the other hand, material (and interface) optimization may constitute an interesting alternative route for further voltage scaling. By optimizing the composition and stoichiometry, less than 1.5V switching has indeed been obtained even for 150nm films. It is argued that an important material parameter affecting low-voltage switching behavior is the ferroelectric domain configuration and presence/absence of mobile domain walls in the PZT film.

Type
Research Article
Copyright
Copyright © Materials Research Society 1999

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References

REFERENCES

1. Tuttle, B.A., in Thin Film Ferroelectric materials and Devices, edited by Ramesh, R., Kluwer, Boston, MA, 1997, pp.145165.Google Scholar
2. The superior low-voltage switching of SBT was attributed to lower Ec and also the possibility to make thinner (<100nm) films of good quality, see e.g.: Scott, J.F., Ross, F.M., Araujo, C.A. Paz de, Scoot, M.C., and Huffman, M., MRS Bulleting, 21 (7), pp.3339 (1996). For film thicknesses of, SBT shows switching already at 1V (while -2V is required for saturated switching), see [17].Google Scholar
3. Norga, G.J., , L., Wouters, D.J., Bartic, A., and Maes, H. E., this proceedings.Google Scholar
4. Tsai, F. and Cowley, J.M., App.Phys.Lett. 65(15), pp.19061908 (1994).Google Scholar
5. Larsen, P.K., Dormans, G.J.M., Taylor, D.J., and Veldhoven, P.J. van, J.Appl.Phys. 76(4), p.24052413 (1994).Google Scholar
6. Ahn, C.H., Tybell, T., Triscone, J.-M., presented at the ECAPD IV'98 – ISAF XI '98 -Electroceramics VI '98 joined conference, Montreux, (Switzerland), Aug. 1998.Google Scholar
7. Hidaka, T., Marayuma, T., Sakai, I., Saito, M., Wills, L.A., Hiskes, R., Dicarolis, S.A., and Amano, J., Integrated Ferroelectrics 17(1-4), proceedings of the 9th International Symposium on Integrated Ferroelectric, March 1997, Santa Fe (NM), p.319 (1997).Google Scholar
8. Bjnrmander, C., Sreenivas, K., Duan, M., Grishin, A.M., and Rao, K.V., Appl.Phys.Lett. 66 (19), pp. 24932495 (1995).Google Scholar
9. Sanchez, L.E., Wu, S.-Y., and Naik, I.K., Appl.Phys.Lett. 56 (24), pp. 23992401 (1990).Google Scholar
10. Amanuma, K., Mori, T., Hase, T., Sakuma, T., Ochi, A., and Miyasaka, Y., Jpn. J.Appl.Phys. Vol.32 (1993), pp.41504153.Google Scholar
11. Aoki, K., Fukuda, Y., Numara, K., and Nishimura, A., Jpn. J.Appl.Phys., Vol.34 (1995), pp.746751.Google Scholar
12. Wouters, D.J., Norga, G.J., Beckers, F., Bogaerts, L., presented at the 9th International Symposium on Integrated Ferroelectrics, March 1997, Santa Fe, NM (unpublished).Google Scholar
13. Wouters, D.J., Willems, G., Lee, E.G., Maes, H.E., Integrated Ferroelectrics, 15, pp.7987 (1997).Google Scholar
14. Wouters, D.J., Norga, G.J., and Maes, H.E., presented at the 10th International Symposium on Integrated Ferroelectrics, March 1998, Monterey, CA (unpublished).Google Scholar
15. Ozaki, K., Nagata, K., J.of The American Ceramic Society, 56, No.2, pp.8286 (1973).Google Scholar
16. Desu, S.B., Peng, C.H., Kammerdiner, L., Schuele, P.J., in Ferroelectric Thin Films, edited by Meyers, E.R. and Kingon, A. (Mat.Res.Soc.Symp.Proc. Vol.200, Pittsburgh, PA, 1990), pp.319324.Google Scholar
17. Amanuma, K., Kunio, T., Jpn. J.Appl.Phys., 35 (1996), pp.52295231.Google Scholar
18. The term poling was originally used in the context of polarization alignment in ferroelectric ceramics, required to obtain pyroelectric and piezoelectric response. For these purposes, the resultant polarization alignment was more important than the concurrent modification of the domain structure. In our case, on the other hand, the modification of the domain structure is more important as it influences subsequent switching behavior. However, as both processes go together as a result of a high voltage application, we call both of them (electrical) “poling” (the term electrical contrasts with possible stress or thermal poling).Google Scholar