Investigating the reliability of SiC MOSFET body diodes using Fourier series modelling

Abstract

Using the Fourier series solution to the ambipolar diffusion equation, the robustness of the body diodes of SiC MOSFETs during reverse recovery has been studied. Parasitic bipolar latch-up during the reverse recovery of the body diode is a possible if there is sufficient base current and voltage drop across the body resistance to forward bias the parasitic BJT. SiC MOSFETs have very low carrier lifetime and thin epitaxial drift layers, which means that the dV/dt during the recovery of the body diode can be quite high. This dV/dt coupled with the parasitic drain-to-body capacitance can cause a body current. The paper introduces a new way of assessing the reliability of SiC MOSFETs during the reverse recovery of the body diode. The impact of switching rates, parasitic inductances and carrier lifetime on the activation of the parasitic BJT has been studied.

Enhance Reliability of Semiconductor Devices in Power Converters

“…Thus, both the on-resistance and forward voltage of the body diode would increase [38]. The on-resistance [35], forward voltage [39], and drain leakage current [25] are considered as indicators for the body diode degradation. Although some new packaging technologies are introduced, especially for power modules to enhance the reliability, still, conventional packaging and wire bonding techniques are utilized for the majority of commercial IGBT and SiC MOSFET.…”

Physics-based modelling and experimental characterisation of parasitic turn-on in IGBTs

“…Multiple publications have detailed how the minority carrier distribution profile in the drift region of bipolar devices can be modelled using the Fourier series construction of Ambipolar Diffusion Equation (ADE) [3][4][5][6][7][8][9][10][11][12][13][14][15][16]. The IGBT model is developed based on the drift and diffusion equations of carriers and takes the displacement current into account.…”

Modeling of temperature dependent parasitic gate turn-on in silicon IGBTs

“…The use of the Fourier series to reconstruct the ambipolar diffusion equation in the drift region of a bipolar device has been detailed in multiple publications [3][4][5][6][7][8][9][10][11][12][13][14][15][16][17]. Using the drift and diffusion current equations, the behavior of the charge storage region is explained in the model which also takes the displacement current resulting from voltage dependent depletion widths into account.…”