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Iridium Electrodes for Ferroelectric Capacitors Deposited by Liquid-Delivery MOCVD

Published online by Cambridge University Press:  26 February 2011

Yves Ritterhaus ,
Tetyana Hur'yeva ,
Marco Lisker  and
Edmund Paul Burte
Yves Ritterhaus
Affiliation:
[email protected], University of Magdeburg, IMOS, Universitäts Platz 2, Magdeburg, N/A, 39106, Germany, 00493916712761, 00493916712103
Tetyana Hur'yeva
Affiliation:
[email protected], University of Magdeburg, IMOS, Germany
Marco Lisker
Affiliation:
[email protected], University of Magdeburg, IMOS, Germany
Edmund Paul Burte
Affiliation:
[email protected], University of Magdeburg, IMOS, Germany
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Abstract

Thin iridium films are required as electrode material for ferroelectric capacitors. SBT or PZT are often used as ferroelectric material in such capacitors. The PZT based non-volatile ferroelectric random access memories show better fatigue characteristics if platinum is replaced by iridium as electrode material. Metalorganic chemical vapor deposition (MOCVD) was used for the deposition because of the superior step coverage on three-dimensional structures compared to the conventional physical vapor deposition processes of metal layers. Particularly, in memory fabrication, good step coverage is essential. The iridium films were deposited on different substrates at temperatures of 300 – 500 °C by liquid-delivery MOCVD. The precursor Ir(EtCp)(1,5COD) [iridium(ethylcyclopentadienyl)(1,5-cyclooctadiene)] was diluted in toluene (0.1 M concentration) for the deposition experiments. The iridium films were deposited onto TiO2/SiO2/Si-, SiO2/Si-, and Si-substrates to compare the iridium film properties on different substrates. The growth conditions like oxygen flow, growth temperature, and reactor pressure were varied. The growth rates were in a range between 0.05 and 4.6 nm per minute. We found that the growth rates were highly influenced by the oxygen flow and the substrate material. Oxygen assisted the decomposition of the precursor, and carbon and hydrogen of the organic source were oxidized, which suppressed its incorporation into the iridium layer. Annealing in an oxidizing ambient at temperatures above 700 °C resulted in an increased oxidation of the films as proved by XRD analyses. The resistivity of the films was determined by the Van-der-Pauw method. Low resistivities of 7 – 70 µΩcm were obtained for the as-deposited iridium films.

Keywords

Irchemical vapor deposition (CVD) (deposition)x-ray diffraction (XRD)
Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 902: Symposium T – Ferroelectric Thin Films XIII , 2005 , 0902-T03-33
Copyright
Copyright © Materials Research Society 2006

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