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Effect of multi-layered bottom electrodes on the orientation of stronium-doped lead zirconate titanate thin films

Madhu Bhaskaran 1Sharath Sriram 1Ken T. Short 2Anthony S. Holland 1

1. RMIT University, Sch. of Elec. and Comp. Engg., Microelectronics and Materials Technology Centre (RMIT), GPO Box 2476V, Melbourne, Victoria, Melbourne 3001, Australia
2. Australian Nuclear Science and Technology Organisation, Institute of Material Science and Engg. (ANSTO), PMB 1, Menai, New South Wales, Sydney 2234, Australia


This paper discusses the results from Bragg-Brentano X-ray diffraction (XRD) and glancing angle X-ray diffraction (GA-XRD) analysis of piezoelectric strontium-doped lead zirconate titanate (PSZT) thin films deposited on multi-layer coatings on silicon. The films were deposited by RF magnetron sputtering, and a metal coated substrate was desired to exploit the pronounced piezoelectric effect that is theoretically expected normal to the substrate. This highlighted the influence that the bottom electrode architecture had on the final crystalline structure and surface roughness of the deposited thin films. A number of bottom electrode architectures were used, with the uppermost metal layer on which PSZT was deposited being gold or platinum. The choice and the thickness of the intermediate adhesion layers influenced the intensity, and in some cases, the presence of the desired perovskite peaks.

Gold was chosen as its lattice co-efficients were closely matched to that of PSZT; and considering the gold-silicon eutectic point of 363 ºC, deposition on gold coated substrates was limited to 300 ºC. Inter-diffusion between gold, the titanium adhesion layer, and silicon was observed. A silicon dioxide layer was introduced to overcome the inter-diffusion, and appeared to have an effect on the final crystalline state, which was determined using XRD.

For platinum bottom electrodes (which are preferred choice in literature), a number of multi-layer combinations were experimented with; these included different combinations and thicknesses of platinum, titanium, titanium dioxide, and silicon dioxide. Depositions were carried out at temperatures ranging from 500 ºC to 750 ºC, with post deposition annealing performed in certain cases. This paper shows the different reactions which occur, and highlights cases in which changing the bottom electrode architecture distinguished the dominant perovskite orientation.


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Presentation: Poster at E-MRS Fall Meeting 2007, Symposium H, by Madhu Bhaskaran
See On-line Journal of E-MRS Fall Meeting 2007

Submitted: 2007-05-01 10:27
Revised:   2009-06-07 00:44