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Entwicklung eines Hochtemperatur-Trench-Kondensators mit Hilfe von Methoden der Atomlagenabscheidung

: Dietz, Dorothee
: Vogt, Holger; Fiedler, Horst-Lothar

Duisburg-Essen, 2017, XXVI, 124 S.
Duisburg-Essen, Univ., Diss., 2017
Fraunhofer IMS ()

Subject of this thesis is the development and characterization of a high temperature trench capacitor. In the application of deep drilling, aerospace or in the automobile industry, more and more passives are needed, which have to withstand temperatures up to 300 °C. In the frame of this work, the development of a capacitor is investigated, which shows a low leakage current at elevated temperatures and a breakdown voltage sufficiently above the operating voltage at the same time. Furthermore, the capacitor shall show a large capacitance per unit area. According to the well known formula for the parallel plate capacitor, the capacitance value shows a linear increase with the relative permittivity and the area of the dielectric, respectively, and a linear decrease with the thickness of the dielectric layer. A further decrease of the thickness of the dielectric layer to enhance the capacitance per unit area is limited by the fact, that in the high temperature case the leakage current, induced by defects in the dielectric layer, increases dramatically with thinner layer. Thus, the remaining two parameters, area and permittivity, are used to get good capacitor performance at elevated temperatures. To get a preferably large capacitor surface area, the capacitor is 3D-integrated. Deep reactive ion etching (DRIE) is used to etch different structures into the substrate, to increase the capacitor area. In addition, high-k materials are used as dielectrics, instead of the common used SiO2. The combination of different dielectric materials deposited via atomic layer deposition (ALD) and the 3D-integration technique gives an excellent opportunity to enhance the capacitor performance at high temperatures. ALD is chosen, because it is a very homogenous and conformal deposition technique, which is needed due to the high aspect ratios of the etched structures. In scope of this work, the process flow is developed and every step is optimized. Subsequently, the processed structures are electrically characterized. Current-voltage measurements at different temperatures, with different material combinations and 3D-configurations give some indication of each leakage current and each breakdown voltage. Capacitance-voltage measurements give the capacitance per unit area and the voltage and temperature dependency of the capacitors.