Selected Publications - 2008:

1) Microscopic model for the nonlinear behavior of high-k metal-insulator-metal capacitors

Ch. Wenger¹, G. Lupina¹, M. Lukosius¹, O. Seifarth¹, H.-J. Müssig¹, S. Pasko², and Ch. Lohe²

¹ IHP, Im Technologiepark 25, 15236 Frankfurt (Oder), Germany

² AIXTRON AG, 52072 Aachen, Germany

Journal of Applied Physics 103, 104103 (2008)

(Received 23 January 2008; accepted 6 March 2008; published online 22 May 2008)

The achievement of sufficient capacitance-voltage linearity in metal-insulator-metal (MIM) capacitors with high permittivity (high-k) dielectrics is still a challenge, as the origin of the nonlinear behavior is still unclear. Based on fundamental physical mechanisms, such as electrostriction, Coulomb interaction between electrodes, and nonlinear optical effects, a microscopic model, which describes the nonlinearities in capacitance-voltage characteristics of high-k MIM capacitors, will be presented. The extended model, which includes stacked high-k dielectrics and interfacial layers, is able to predict the quadratic voltage capacitance coefficients as a function of the dielectric constant. The calculated coefficients are in suitable agreement with the experimental values of Al₂O₃-, Y₂O₃-, HfO₂-, and Pr₂Ti₂O₇-based MIM capacitors. © 2008 American Institute of Physics.

PDF published by Journal of Applied Physics available online at jap.aip.org

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2) Atomic Vapor Deposition of Strontium Tantalate Films For MIM Applications

Mindaugas Lukosius, Christian Wenger, Sergej Pasko, Ioan Costina, Jarek Dabrowski, Roland Sorge, Hans-Joachim Müssig, and Christoph Lohe

IEEE TRANSACTIONS ON ELECTRON DEVICES, VOL. 55, NO. 8, AUGUST 2008

Sr–Ta–O thin films were deposited as high-k dielectrics for metal–insulator–metal applications on 200-mm TiN/Si(100) substrates from a single-source Sr[Ta(OEt)₅ (methoxyethoxide)]₂ precursor using atomic vapor deposition technique. The variation of process pressure affects the Sr/Ta ratio in the films. Dielectric layers with optimized composition of Sr₂Ta₂O_7−δ possess a capacitance density of 5.5 fF/μm² in combination with a voltage linearity coefficient of 80 ppm/V² and a quality factor of 52 at 10 kHz. The optimized films with thickness of 30 nm exhibit a leakage current density of 7 · 10^-9 A/cm² at 2 V and a breakdown strength of 3.2 MV/cm, and, therefore, meet the requirements of the current International Roadmap for Semiconductors.

PDF published by IEEE Xplore available online at ieeexplore.ieee.org/xpl/RecentIssue.jsp

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3) Atomic Vapor Deposition of Titanium Nitride as Metal Electrodes for Gate-last CMOS and MIM Devices

Mindaugas Lukosius, Christian Wenger, Sergej Pasko, Hans-Joachim Müssig, Bernhard Seitzinger, and Christoph Lohe

Chemical Vapor Deposition 2008, 14, 1–6

Pure and diluted Ti[N(Et)₂]₄ precursors are used to grow TiN layers at 400-600 °C by using atomic vapor deposition (AVD^®). The composition, microstructure, and electrical properties of TiN films with various thicknesses are investigated. The determined work function of 4.7 eV indicates the possibility of using AVD^®-grown TiN as a metal gate electrode for PMOSFET and metal-insulator-metal (MIM) devices. TiN/HfO₂/SiO₂ stacks are integrated into gate-last PMOS transistors, and the extracted parameters are compared to poly-Si/SiO₂ reference transistors. The optimized films grown at 400 °C with a thickness of 20nm exhibit a resistivity of 400 μΩcm.

PDF published by Chemical Vapor Deposition available online at www.wiley-vch.de/publish/en/journals/alphabeticIndex/2112/

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