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Metalorganic chemical vapor deposition of very thin Pb(Zr,Ti)O3 thin films at low temperatures for high-density ferroelectric memory applications

Published online by Cambridge University Press:  31 January 2011

Hye Ryoung Kim ,
Seehwa Jeong ,
Chung Bae Jeon ,
Oh Seong Kwon ,
Cheol Seong Hwang ,
Young Ki Han ,
Doo Young Yang  and
Ki Young Oh
Hye Ryoung Kim
Affiliation:
School of Materials Science and Engineering and Inter-university Semiconductor Research Center, Seoul National University, San #56–1 Shillim-dong, Kwanak-ku, Seoul, 151–742, Korea
Seehwa Jeong
Affiliation:
School of Materials Science and Engineering and Inter-university Semiconductor Research Center, Seoul National University, San #56–1 Shillim-dong, Kwanak-ku, Seoul, 151–742, Korea
Chung Bae Jeon
Affiliation:
School of Materials Science and Engineering and Inter-university Semiconductor Research Center, Seoul National University, San #56–1 Shillim-dong, Kwanak-ku, Seoul, 151–742, Korea
Oh Seong Kwon
Affiliation:
School of Materials Science and Engineering and Inter-university Semiconductor Research Center, Seoul National University, San #56–1 Shillim-dong, Kwanak-ku, Seoul, 151–742, Korea
Cheol Seong Hwang
Affiliation:
School of Materials Science and Engineering and Inter-university Semiconductor Research Center, Seoul National University, San #56–1 Shillim-dong, Kwanak-ku, Seoul, 151–742, Korea
Young Ki Han
Affiliation:
Jusung Engineering LTD., #49, Neungpyeong-Ri, Opo-Myeun, Kwangju-Gun, Kyunggi-Do, 464–890, Korea
Doo Young Yang
Affiliation:
Jusung Engineering LTD., #49, Neungpyeong-Ri, Opo-Myeun, Kwangju-Gun, Kyunggi-Do, 464–890, Korea
Ki Young Oh
Affiliation:
Jusung Engineering LTD., #49, Neungpyeong-Ri, Opo-Myeun, Kwangju-Gun, Kyunggi-Do, 464–890, Korea
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Abstract

The metalorganic chemical vapor deposition of very thin (<50 nm) Pb(Zr,Ti)O3 (PZT) thin films was performed for high density (>32 mega bit) ferroelectric memory devices. The growth temperatures were set between 450 and 530 °C to obtain a smooth surface morphology and prevent damage to the underlying reaction barrier layer. The average grain size of a 50-nm-thick film on a Pt electrode was about 34 nm with a size distribution (σ2) of 11 nm. These values are much smaller than the sol-gel-derived PZT films (55 and 25 nm, respectively). Very thin films with a thickness of approximately 30 nm were prepared at wafer temperatures ranging from 500 to 525 °C. Even with the very small thickness, the films showed good ferroelectric properties with a typical remanent polarization from 10 to 15 μC/cm2 and an extremely low coercive voltage of 0.3 V. However, the leakage current density was rather high resulting in nonsaturating polarization versus voltage curves. Even though good ferroelectric properties were obtained, the formation of PtxPby alloys on top of the Pt electrode was consistently observed. This precludes the reliable control of film composition and electrical performance. The adoption of an Ir electrode successfully eliminated intermetallic alloy formation and resulted in better and reproducible process control. A 50-nm-thick PZT film on an Ir/IrO2/SiO2/Si substrate also showed a reasonable ferroelectric performance.

Type
Articles
Information
Journal of Materials Research , Volume 16 , Issue 12 , December 2001 , pp. 3583 - 3591
Copyright
Copyright © Materials Research Society 2001

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