Berlin 2008 – scientific programme

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DS: Fachverband Dünne Schichten

DS 23: High-k Dielectric Materials - Synthesis, Properties, Applications
The posters can also be presented at Poster A on Tuesday morning (DS poster session).

DS 23.1: Poster

Wednesday, February 27, 2008, 18:30–20:30, Poster C

Leakage current in high-k thin film capacitor stacks — •Herbert Schroeder — IEM im Institut für Festkörperforschung und CNI, Forschungszentrum Jülich GmbH, D-52425 Jülich

High-permittivity thin insulating films of the perovskite-type mixed-oxides such as SrTiO₃ or (Ba,Sr)TiO₃ are candidates as capacitor dielectrics in advanced DRAM cells and as new gate materials in MOSFETs (see ITRS Roadmap). One of the most important issues for these applications is a sufficiently low leakage current to avoid malfunction of the devices. Although a large number of experimental data on leakage through metal-insulator-metal (MIM) thin film capacitor structures is published for perowskite-type mixed oxides, the mechanistic interpretation is quite inconsistent. In this contribution the experimental data will be compared to simulation studies for an advanced leakage current model combining the electronic carrier injection/ejection at the electrode interfaces (described by thermionic emission) with the film conduction properties of the thin dielectric film (modelled as wide band gap semiconductor). Many parameters are varied: Besides the externally given electric field, dielectric thickness and temperature, these are the usually unknown defect properties [type (donor, acceptor), concentration and in-gap energy level as well as type and degree of compensation] and that of the electrode interfaces. From the resulting trends guidelines for a low leakage MIM stack with high effective permittivity are extracted.