Berlin 2008 – scientific programme

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BP: Fachverband Biologische Physik

BP 23: Electrical Stimulation and Recording

BP 23.2: Talk

Thursday, February 28, 2008, 12:15–12:30, PC 203

Very high-k oxide dielectric on silicon chip for capacitive stimulation of nerve cells — •Biljana Mesic and Herbert Schroeder — IEM im Institut für Festkörperforschung und CNI, Forschungszentrum Jülich GmbH, D-52425 Jülich

Thin insulating films of the perovskite-type mixed-oxides such as (Ba,Sr)TiO3 or SrTiO3 have very large dielectric constants of k>200. Compared to the materials presently used for capacitive stimulation of nerve cells directly on silicon chips such as TiO2 or HfO2 with about k=40, such enlarged capacitance would allow increased stimulation. We have fabricated an electrode stack directly on a conducting, highly doped silicon wafer. Due to the conductive diffusion barrier layer included in the stack it is stable up to 600°C, which then allows high temperature deposition of perovskite-type mixed-oxides with very high dielectric constants up to k=450.

In this contribution we report the fabrication of the thin film electrode stack on the silicon chip which then was used as bottom electrode for a capacitor with thin film oxide dielectric (BST) and platinum top electrodes. Detailed electrical characterization (capacitance, leakage current) is also presented proving the desired properties.