Leakage Current Degradation Due to Ion Drift and Diffusion in Tantalum and Niobium Oxide Capacitors

• Autorzy: Kuparowitz M. , Sedlakova V. , Grmela L.

Identyfikatory

DOI

10.1515/mms-2017-0034

• Języki publikacji: EN

Abstrakty

EN

High temperature and high electric field applications in tantalum and niobium capacitors are limited by the mechanism of ion migration and field crystallization in a tantalum or niobium pentoxide insulating layer. The study of leakage current (DCL) variation in time as a result of increasing temperature and electric field might provide information about the physical mechanism of degradation. The experiments were performed on tantalum and niobium oxide capacitors at temperatures of about 125°C and applied voltages ranging up to rated voltages of 35 V and 16 V for tantalum and niobium oxide capacitors, respectively. Homogeneous distribution of oxygen vacancies acting as positive ions within the pentoxide layer was assumed before the experiments. DCL vs. time characteristics at a fixed temperature have several phases. At the beginning of ageing the DCL increases exponentially with time. In this period ions in the insulating layer are being moved in the electric field by drift only. Due to that the concentration of ions near the cathode increases producing a positively charged region near the cathode. The electric field near the cathode increases and the potential barrier between the cathode and insulating layer decreases which results in increasing DCL. However, redistribution of positive ions in the insulator layer leads to creation of a ion concentration gradient which results in a gradual increase of the ion diffusion current in the direction opposite to the ion drift current component. The equilibrium between the two for a given temperature and electric field results in saturation of the leakage current value. DCL vs. time characteristics are described by the exponential stretched law. We found that during the initial part of ageing an exponent n = 1 applies. That corresponds to the ion drift motion only. After long-time application of the electric field at a high temperature the DCL vs. time characteristics are described by the exponential stretched law with an exponent n = 0.5. Here, the equilibrium between the ion drift and diffusion is achieved. The process of leakage current degradation is therefore partially reversible. When the external electric field is lowered, or the samples are shortened, the leakage current for a given voltage decreases with time and the DCL vs. time characteristics are described by the exponential stretched law with an exponent n = 0.5, thus the ion redistribution by diffusion becomes dominant.

Słowa kluczowe

EN

niobium oxide capacitors; tantalum capacitors; leakage current; ion diffusion; ion drift

• Wydawca: Komitet Metrologii i Aparatury Naukowej PAN
• Czasopismo: Metrology and Measurement Systems
• Rocznik: 2017
• Tom: Vol. 24, nr 2
• Strony: 255--264
• Opis fizyczny: Bibliogr. 13 poz., rys., wykr.

Twórcy

autor

Kuparowitz M.

• Brno University of Technology, Faculty of Electrical Engineering and Communication, Technicka 8, Brno, Czech Republic

autor

Sedlakova V.

• Brno University of Technology, Faculty of Electrical Engineering and Communication, Technicka 8, Brno, Czech Republic

autor

Grmela L.

• Brno University of Technology, Faculty of Electrical Engineering and Communication, Technicka 8, Brno, Czech Republic

Bibliografia

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• [5] Pavelka, J., Sikula, J., Vasina, P., Sedlakova, V., Tacano, M., Hashiguchi, S. (2002). Noise and transport characterisation of tantalum capacitors. Microelectronics Reliability, 42, 841-847.
• [6] Teverovsky, A. (2010). Effect of Post-HALT Annealing on Leakage Currents in Solid Tantalum Capacitors, CARTS USA 2010, 43-59.
• [7] Teverovsky, A. (2010). Degradation of leakage currents in solid tantalum capacitors under steady-state bias conditions. Electronic Components and Technology Conference (ECTC). Proc. 60th, 2010, 752-757.
• [8] Zednicek, T., Sikula, J., Leibovitz, H. (2009). A Study of Field Crystallization in Tantalum Capacitors and its effect on DCL and Reliability. 29th CARTS 2009, Jacksonville, FL, 5.3.1-11.
• [9] Sikula, J., Sedlakova, V., Navarova, H., Hlavka, J., Tacano, M., Zednicek, T. (2008). Tantalum and Niobium Oxide High Voltage Capacitors: Field Crystallization and Leakage Current Kinetics. CARTS Europe 2008, Helsinki, Finland, Oct. 20-23, 2008, 267-276.
• [10] Laleko, V.A., Odinets, L.L., Stefanovich, G.B. (1982) Ionic current and kinetics of activation of the conductivity of anodic oxide films on tantalum in strong electric fields. Soviet Electrochemistry, 18, 743-746.
• [11] Chaneliere, C., et al. (1998). Tantalum pentoxide (Ta2O5) thin films for advanced dielectric applications. Material Science and Eng., R22, 269-322.
• [12] Sikula, J., Sedlakova, V., Navarova, H., Kopecky, M., Zednicek, T. (2011). Ion Diffusion and Field Crystallization in Niobium Oxide Capacitors. CARTS Europe 2011, Nice, France, 33-41.
• [13] Elhadidy, H., Grill, R., Franc, J., Sik, O., Moravec, P., Schneeweiss, O. (2015). Ion electromigration in CdTe Schottky metal-semiconductor-metal structure. Solid State Ionics, 278, 20-25.

Uwagi

EN

Research described in this paper was financed by Czech Ministry of Education in the frame of National Sustainability Program under grant LO1401. For research, the infrastructure of the SIX Center was used.

PL

Opracowanie ze środków MNiSW w ramach umowy 812/P-DUN/2016 na działalność upowszechniającą naukę (zadania 2017).