Poole–Frenkel Emission Saturation and Its Effects on Time-to-Failure in Ta-Ta2O5-MnO2 Capacitors

Abstract EN

I-V characterization of Ta-Ta2O5-MnO2 capacitors was investigated at different temperatures, and Poole–Frenkel (PF) emission saturation was experimentally observed.

Under the saturation voltage, the I-V curves at different temperature converged, and the temperature dependency was vanished.

Above the saturation voltage, the leakage current was decreasing as the temperature increased.

In order to evaluate the effects of saturation voltages (VS) on time-to-failure (TTF) of the capacitors, VS were first determined at +2°C and +25°C, then voltage accelerating tests were conducted at 85°C under 1.6 times of rated voltage.

The distribution of VS and TTF of the samples were plotted and compared.

It was shown that samples with lower saturation voltage failed earlier in the distribution of time-dependent dielectric breakdown.

Comparing conventional methods for evaluating the quality of tantalum capacitors by measuring the leakage current at elevated temperature, the nondestructive measurement of saturation voltage at +2°C and +25°C may provide a novel and practicing approach tool to screening out capacitors with defected Ta2O5 layers.