Regensburg 2010 – scientific programme
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HL: Fachverband Halbleiterphysik
HL 31: Poster I: Devices, Quantum Dots and Quantum Wires
HL 31.6: Poster
Tuesday, March 23, 2010, 18:30–20:30, Poster D1
Oxygen vacancies in ultrathin gate dielectric of MOSFETs and their influence on the leakage current: an ab initio investigation — •Ebrahim Nadimi1,2, Philipp Plänitz1,2, Christian Radehaus2, and Michael Schreiber1 — 1Institut für Physik, Technische Universität Chemnitz, D-09107 Chemnitz, Germany — 2GWT-TUD GmbH - Geschäftsstelle Chemnitz, Annaberger Str. 240, D-09125 Chemnitz, Germany
Oxygen vacancies are known to be the dominant defect in dielectric layer of the MOSFET transistors and are responsible for stress induced leakage current (SILC) as well as degradation of the the gate oxide. In this work a combination of density functional theory (DFT) within the generalized gradient approximation (GGA) and non-equilibrium Green*s function formalism (NEGF) as implemented in ATOMISTIX TOOLKIT 2.0 (ATK) has been applied to investigate neutral oxygen vacancies in the vicinity of Si/SiO2 interface. The formation energy of single and double oxygen vacancies at different layers of the oxide, the correlation between the position of vacancies and the carrier tunneling probability as well as the tunneling probability through vacancy chains have been investigated. The single vacancies are shown to be energetically more stable at the Si/SiO2 interface, where unfortunately they have destructive impact on the leakage current. The formation energies of different arrangements of two vacancies indicate an attractive interaction between them. A chain of five vacancies is shown to drastically increase the leakage and could build a percolation path which results in an electrical breakdown of the dielectric.