Regensburg 2010 – scientific programme

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DS: Fachverband Dünne Schichten

DS 23: High-k and Low-k Dielectrics I (Joint Session DS/DF)

DS 23.2: Talk

Wednesday, March 24, 2010, 09:45–10:00, H8

The influence of elastic and inelastic processes on trap assisted tunnelling through thin dielectric films — •Grzegorz Kozlowski, Jarek Dabrowski, Piotr Dudek, Gunther Lippert, and Grzegorz Lupina — IHP, Im Technologiepark 25, 15236 Frankfurt (Oder) , Germany

Impurities or structural imperfections of the crystal may introduce discrete electronic states (or a band when defects interact with one another) into the band gap of the dielectric. Electrically active defects can be used in a trap assisted tunnelling (TAT) process giving a noticeable contribution to the leakage and to the total current.

We developed a simple quantum mechanical model to investigate the role of defects in leakage current through thin dielectric films for future DRAM applications. The influence of image force as well as a possible charge state of an empty trap was considered. The results of numerical simulation were used to characterize the electrical behaviour of thin dielectric films at different temperatures. The temperature dependence may come from two phenomena. The first one is the Boltzmann distribution of charge carriers in the electrodes. In a limited way one can reproduce the temperature dependence of the leakage by considering various distribution of defects in energy and position in the film. This approach is however insufficient to reproduce the dependence in the whole regime of applied voltages. We thus expanded our model by including an additional type of process, i.e. the electron-phonon coupling which gave rise to non-radiative multiphonon processes.