Time-Dependent Dielectric Breakdown of Commercial 1.2 kV 4H-SiC Power MOSFETs

• Main Authors: Tianshi Liu, Shengnan Zhu, Marvin H. White, Arash Salemi, David Sheridan, Anant K. Agarwal
• Format: Article
• Language: English
• Published: IEEE 2021-01-01
• Series: IEEE Journal of the Electron Devices Society
• Subjects: Electron and hole trapping; impact ionization; gate oxide reliability; lifetime; silicon carbide (SiC) power MOSFETs; time-dependent dielectric breakdown (TDDB)
• Online Access: https://ieeexplore.ieee.org/document/9463426/

Constant-voltage time-dependent dielectric breakdown (TDDB) measurements are performed on recently manufactured commercial 1.2 kV 4H-SiC power metal-oxide-semiconductor (MOS) field-effect transistors (MOSFETs) from three vendors. Abrupt changes of the electric field acceleration parameters (<inline-formula> <tex-math notation="LaTeX">$\gamma $ </tex-math></inline-formula>) are observed at oxide electric fields (<inline-formula> <tex-math notation="LaTeX">$E_{ox}$ </tex-math></inline-formula>) around 8.5 MV/cm to 9 MV/cm for all commercial MOSFETs. Gate leakage currents and threshold voltage shifts are also monitored under different oxide fields (<inline-formula> <tex-math notation="LaTeX">$E_{ox}= {\mathrm {8 MV/cm}}$ </tex-math></inline-formula> and 10 MV/cm). The results suggest the failure mode under high oxide electric field is modified by impact ionization or Anode Hole Injection (AHI) induced hole trapping. This observation agrees with previously published oxide reliability studies on SiC MOSFETs and suggests that constant-voltage TDDB measurements need to be carefully performed under low oxide fields to avoid lifetime overestimation caused by hole trapping. The extrapolated <inline-formula> <tex-math notation="LaTeX">$t_{63\%}$ </tex-math></inline-formula> lifetimes (times to 63&#x0025; failures) from TDDB measurements performed at <inline-formula> <tex-math notation="LaTeX">$E_{ox} &lt; {\mathrm {8.5 MV/cm}}$ </tex-math></inline-formula> are longer than 10⁸ hours at 150&#x00B0;C for all vendors. The predicted lifetimes at <inline-formula> <tex-math notation="LaTeX">$E_{ox}= {\mathrm {4 MV/cm}}$ </tex-math></inline-formula> demonstrate more than 10⁵ times increases than the oxide lifetimes reported a decade ago, showing promising progress in SiC technology.