Hydrogen infiltration into BaTiO₃-based dielectrics for multi-layer ceramic capacitors under highly accelerated temperature and humidity stress test

Abstract

To make electrical devices, such as smartphones and automotive devices, more functional, the mechanism of electrical reliability in multi-layer ceramic capacitors (MLCCs) under high temperature, high humidity, and electric field bias environments has been studied. Although it has been presumed that hydrogen influences this mechanism, it is difficult to analyze hydrogen itself. Therefore, we investigated BaTiO 3 -based dielectrics in which the leakage current increases by conducting highly accelerated temperature and humidity stress tests using heavy water (D 2 O) as a tracer instead of light water (H 2 O) and secondary ion mass spectrometry analysis. We report the detection of deuterium in the dielectrics between the inner electrodes where the leakage current increased, and deuterium was biased toward the internal electrode on the cathode side. These findings can help further improve the reliability of MLCCs.

Ferroelectric polarization of tetragonal BiFeO3—an approach from DFT calculations for BiFeO3–BaTiO3 superlattices—

“…Moreover, BiFeO 3 has a Curie temperature (T C ) of 830 °C, 47,48) which is much higher than that of PbTiO 3 (495 °C49) ) Barium titanate, BaTiO 3 , play an essential role for ceramic capacitor applications 50,51) and also for ferroelectricderived functions. [52][53][54][55][56] In tetragonal P4mm symmetry, Ti and Ba are displaced cooperatively along the polar c axis, leading to a P s of 26-29 μC cm −2 . 57,58) For (1−x) BiFeO 3 -x BaTiO 3 ceramics, structural analysis showed that an x increase changes a crystal symmetry from R3c rhombohedral to pseudo-cubic at ca.…”

Hydrogen migration in BaTiO3-based dielectrics under high humidity and electric field bias

“…In previous studies, it was presumed that when water vapor infiltrated the interface between the anode-side inner electrode and the dielectric, electrolysis occurred at the interface, as shown in the equation below, and D + was attracted to the cathode-side inner electrode by migration through the dielectric. [23][24][25] Considering the results of Fig. 3(a) and the aforementioned presumption, the deuterium in the dielectric is presumed to exist as D +…”

“…It was observed, that deuterium was biased toward the cathode-side inner electrode in the BaTiO 3 -based dielectric exhibiting increased leakage current. 25) Therefore, the increased leakage current in the test can be attributed to either the proton migration at the interstitial sites in the dielectric lattices or the corresponding increase in the electron concentration. 25) The mechanism of proton migration could be either diffusion due to the concentration gradient or drift due to the voltage bias.…”

“…25) Therefore, the increased leakage current in the test can be attributed to either the proton migration at the interstitial sites in the dielectric lattices or the corresponding increase in the electron concentration. 25) The mechanism of proton migration could be either diffusion due to the concentration gradient or drift due to the voltage bias. However, this has not yet been clarified.…”

“…From the results of previous studies, [23][24][25] it was presumed that protons migrate because they are attracted from the anode side to the cathode side. In this study, secondary ion mass spectrometry (SIMS), which can analyze deuterium with a high degree of sensitivity, was used to understand deuterium migration due to the electric field and temperature.…”