Precursors of Gate-Oxide Degradation in Silicon Carbide MOSFETs

Abstract

Gate oxide degradation is more critical in Silicon-Carbide (SiC) MOSFETs than in Silicon (Si) MOSFETs. This is because of the smaller gate oxide thickness and the higher electric field that develops across the gate oxide in SiC MOSFETs. While multiple precursors have been identified for monitoring the gate oxide degradation in Si MOSFETs, very few precursors have been identified for SiC MOSFETs. The purpose of this paper is to demonstrate that gate oxide degradation precursors used in Si MOSFETs: a) threshold voltage, b) gate plateau voltage and c) gate plateau time, can also be used as precursors for SiC MOSFETS. Moreover, all three precursors are found to exhibit a simultaneous increasing trend (during the stress time) leading to an increase in on-state loss, switching loss and switching time of the SiC MOSFET. The existing studies of gate oxide degradation mechanisms in SiC MOSFETs, and their effects on threshold voltage and mobility were extended to correlate a variation of all three precursors using analytical expressions. The increasing trends of precursors were experimentally confirmed by inducing gate oxide degradation in commercial SiC MOSFET samples.

Active Power Cycling Test Bench for SiC Power MOSFETs—Principles, Design, and Implementation

“…In the case of encapsulated power semiconductors (power MOSFETs, diodes, IGBTs, etc.) the main stressors are maximum junction temperature [14], temperature swing during a single thermal cycle [15], blocking voltage [16], relative humidity [17] and gate voltage [18]. Each of these stressors accelerate at least one of the following failure modes, which are typical for encapsulated power semiconductors: solder delamination, solder joint fatigue, bond wire lift-off [19], bond wire heel-cracking [20], brittle cracking [21], corrosion [22], gate oxide time dependent breakdown [23], single event effects [24], etc.…”

A digital‐controlled gate charge detection circuit for short‐circuit protection and condition monitoring of SiC MOSFET

“…Most of these works focused on the static parameters including threshold voltage (V th ), drain-source on-resistance (R DS ,on ), gate leakage current (I GSS ), drain leakage current (I DSS ) and et al [24][25][26][27][28][29], which are normally measured off-line using the semiconductor analyzer like Keysight B1505. Considering the fact that the SiC MOS-FET is used as the switch in the power converter, the dynamic parameters like gate charge (Q g ) [24], Miller plateau voltage (V g p ) [30,31], and switching transition [32] are more practical to be acquired. However, only few works have been conducted on the on-line monitoring circuit of SiC MOSFET using the dynamic parameters.…”

“…[24–29], which are normally measured off‐line using the semiconductor analyzer like Keysight B1505. Considering the fact that the SiC MOSFET is used as the switch in the power converter, the dynamic parameters like gate charge ($$ Q_g$$) [24], Miller plateau voltage ($$ V_{gp}$$) [30, 31], and switching transition [32] are more practical to be acquired. However, only few works have been conducted on the on‐line monitoring circuit of SiC MOSFET using the dynamic parameters.…”

Impact of BTI-Induced Threshold Voltage Shifts in Shoot-Through Currents From Crosstalk in SiC MOSFETs

“…There have been various studies on BTI in SiC MOSFETs [8][9][10][11][12][13][14][15][16][17]. It has widely been reported that VTH recovery occurs after stress removal [8,18,19].…”