Presentation on theme: "National Science Foundation Electrical Degradation in Thin Layer BaTiO 3 : Microchemical Origins and Microstructural Control Clive A. Randall, Pennsylvania."— Presentation transcript:
National Science Foundation Electrical Degradation in Thin Layer BaTiO 3 : Microchemical Origins and Microstructural Control Clive A. Randall, Pennsylvania State University, DMR 0606352 (GOALI) Explanation: Companies such as Kemet are manufacturing multilayer ceramic capacitors using the high permittivity ferroelectric material, Barium Titanate, and nickel electrodes. The materials must be co-processed so the nickel does not oxide and the dielectric maintains a low leakage current. It was found through state-of-the-art electron microscopy studies that a new alloy formed at this interface, and this impacted the roughness and porosity. Through fast firing at rates 50- 100 times greater than typically used, problems associated with this interface could be overcome. Voltage contrast scanning electron microscopy image of a partially degraded multilayer capacitor. Bright contrast is indicative of highly conductive regions within the layers. Outcome: Researchers at Penn State have developed new insights into the conduction and degradation mechanisms controlling ultrathin multilayer ceramic capacitors. Impact: New fast firing processes are found to minimize electrode roughness and porosity and provide an effective manufacturing route for submicron dielectric layer thickness. These findings will continue to aid device miniaturization, which will provide an increase in volumetric efficiency by an order of magnitude. Electrical leakage will also be minimized with this approach, enabling hand- held electronics to have longer battery lifetime, and size reduction provides increased functionality.
National Science Foundation Electrode Discontinuity Characterization in Multilayer Capacitors Clive A. Randall and Elizabeth Dickey, Pennsylvania State University, and Abhijit Gurav, Kemet Corporation, DMR 0606352 The performance of electrical components, such as multilayer ceramic capacitors (MLCC), is controlled by the local heterogeneities, such as electrode discontinuities. Accurate characterization of such defects has been made possible by serially sectioning MLCC cross- section using focused ion beam (FIB). A series of images generated by this technique can be used to reconstruct three-dimensional images, which can reveal the exact shape and size of these electrode discontinuities and make it possible for us to measure electrode continuity more accurately. I-beam MLCC cross-section Serial-sectioning Schematic Three-dimensional MLCC cross-section generated using serially sectioned images
National Science Foundation The presence of electrode discontinuities leads to local enhancement in electric field, which in turn leads to higher leakage current and inferior degradation resistance. This is shown in a finite element simulation in an MLCC microstructure, which shows that the electric field is 4.13 times the average value near the discontinuity. Such studies have a broad impact not only on the capacitor industry, but also on other devices that use multilayer technology, such as multilayer actuators, multilayer varistors, solid oxide fuel cells, etc. Better processing and control of the interface should have a direct impact on these locally high field regions that limit performance in present day devices. Electrode Discontinuity Characterization in Multilayer Capacitors Clive A. Randall and Elizabeth Dickey, Pennsylvania State University, and Abhijit Gurav, Kemet Corporation, DMR 0606352
National Science Foundation Outreach This GOALI (Grant Opportunities for Academic Liaison with Industry) program, by its nature, has an outreach program with the participating companies, in this case Kemet Corporation. In addition to this, the graduate student, Malay Samantaray, participated in workshops that targeted materials, device, and end user companies, such as AVX, Cooper Power, Cabot, Ferro Corporation, Dupont, Intel, Boston Scientific, etc. In terms of educating our student (Malay Samantaray), he participated in an international dielectrics conference in Japan that was organized between the Tokyo Institute of Technology and Penn State, the aim being to have the students talk about their projects and how they can contribute to big societal issues such as energy, sustainability, health etc. Students gained a broad perspective of the international scientific challenges and an appreciation of their future peers in these types of interactions.