Dielectric Permittivity Mapping up to 9GHz Region with Non-Contact Microwave Probe for Ferroelectric Device
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0966-T10-11
Dielectric Permittivity Mapping up to 9GHz Region with Non-Contact Microwave Probe for Ferroelectric Device Hirofumi Kakemoto, Jianyong Li, Takakiyo Harigai, Song-Min Nam, Satoshi Wada, and Takaaki Tsurumi Graduate school of Science and Engineering, Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro, Tokyo, 152-8552, Japan ABSTRACT Direct observations for high frequency microscopic dielectric distributions in cross sections of a multi-layer ceramic capacitor were carried out using non-contact type microwave probe. The measured data were imaged with the raw data and rounding data process. Using microwave reflection intensity mappings from cross sections of multi-layer ceramic capacitor, the dielectric permittivity distribution in micro-region of a multi-layer ceramic capacitor was measured at room temperature. The spatial resolution was experimentally estimated to be about 10 µm from mappings of the dielectric and inner electrode layers in a multi-layer ceramic capacitor. INTRODUCTION Multi - layer ceramic capacitors (MLCCs) have been prepared from BaTiO3 (BT) based material. MLCCs have been recently miniaturized, and usage in high - frequency has been attempted. However it is difficult for designing of MLCCs’ frequency properties, because the dielectric behavior in the local region of BT is not homogeneous as generally reported in the functions of temperature, frequency and electric field. Therefore, high - frequency dielectric measurement on BT in a micro-region should be carried out. However, conventional dielectric measurement techniques are difficult for investigating the local dielectric properties at high frequency region. Therefore, a high - frequency measurement method for the local dielectric properties should be developed.[1,2,3] Recently, near - field scanning microwave microscopy has been developed by Steinhauer et al. using a λ/4 coaxial resonator and a contact probe, and local dielectric properties have been investigated with the contact probe scanning the surface of a sample at 7.2 GHz.[4,5] The non - contact probe was used in this study to measure in a wide frequency range and observe local dielectric properties, hence a microwave reflection (R) intensity was measured to obtain dielectric permittivity (εr) of sample using the non - contact probe. The non - contact probe is useful for preventing resonance phenomena at a high frequency, however, the impedance (Z) of a sample was found to be changed as a function of phase (θ) in an electric field incident for a sample. In a previous study, the accurate θ was adjusted for the measurement conditions, and εr was estimated with a non - contact state probe.[6] In this study, R intensity is measured using a non - contact probe up to 9.4 GHz, and in-plane R intensity mapping is carried out at the R intensity minimum position for a dielectric Transmission line device (MLCC). EXPERIMENT The measurement system was constructed with an oscillator generated using a Gunn diode, a phase (θ) shifter (0-360o), a directional coupler, a detector (diode),
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