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Ca-doped lead zirconate titanate thin film capacitors on base metal nickel on copper foil

Published online by Cambridge University Press:  01 October 2004

Taeyun Kim
Affiliation:
Department of Materials Science and Engineering, North Carolina State University, Raleigh, North Carolina 27695
Angus I. Kingon
Affiliation:
Department of Materials Science and Engineering, North Carolina State University, Raleigh, North Carolina 27695
Jon-Paul Maria
Affiliation:
Department of Materials Science and Engineering, North Carolina State University, Raleigh, North Carolina 27695
Robert T. Croswell
Affiliation:
Motorola Advanced Technology Center, Schaumburg, Illinois 60196
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Abstract

Ca-doped lead zirconate titanate (52/48) thin film capacitors were prepared on electroless nickel-coated copper foils for embedded capacitor applications. The impact of Ca doping and process parameter variations was studied. Ca addition significantly reduced the temperature coefficient of capacitance. Specifically, the temperature variation was reduced to less than 10% between 300 and 580 K through calcium addition. Optimized capacitance densities and loss tangents were 400 nF/cm2 and 0.02, respectively. Crystallization temperatures of 600 °C yielded these optimized electrical properties, while higher temperatures resulted in interfacial reactions. The influence of oxygen partial pressure during crystallization was also studied. Dielectric properties were sensitive to pO2, with optimal properties occurring in a narrow pO2 window centered about 10−3 Torr. The trends with oxygen pressure were mirrored by changes in phase assemblage. Electrical transport across the dielectric layers was not strongly dependent upon doping level. This insensitivity was attributed to a thin interfacial layer present in all samples. Interface analysis using equivalent circuit analogues showed the nature of the interface to be highly resistive (insulating), rather than semiconducting or conducting.

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Articles
Copyright
Copyright © Materials Research Society 2004

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References

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