Reliability Issues of SiC MOSFETs: A Technology for High Temperature Environments

Published

September 20, 2010

Author(s)

Liangchun (. Yu, Greg Dunne, Kevin Matocha, Kin P. Cheung, John S. Suehle, Kuang Sheng

Abstract

The wide-bandgap nature of silicon carbide (SiC) makes it an excellent candidate for applications where high temperature is required. The MOS-controlled power devices are the most favorable structure, however, it is widely believed that silicon oxide on SiC is physically limited, especially at high temperatures. Therefore, experimental measurements of long-term reliability of oxide at high temperatures are necessary. In this work, time-dependent dielectric breakdown (TDDB) measurements are performed on state-of-the-art 4H-SiC MOS capacitors and DMOSFETs with stress temperatures between 225 °C to 375 °C and stress electric fields between 6 to 10 MV/cm. The field acceleration factor is around 1.5 decade/(MV/cm) for all of the temperatures. The thermal activation energy is found to be ~ 0.9 eV independent of the electric field. The area dependence of Weibull slope (β) is discussed and shown to be a possible indication that the oxide quality has not reached the intrinsic regime and further oxide reliability improvements are possible. Since our reliability data contradicts the widely accepted belief that silicon oxide on SiC is fundamentally limited by its smaller conduction band offset compared to Si, a detailed discussion is provided to examine the arguments of the early predictions.

Citation

IEEE Transactions on Device and Materials Reliability

Pub Type

Journals

Keywords

MOS reliability, high temperature, TDDB, SiC, Weibull slope, activation energy, DMOSFET

Citation

Yu, L. , Dunne, G. , Matocha, K. , Cheung, K. , Suehle, J. and Sheng, K. (2010), Reliability Issues of SiC MOSFETs: A Technology for High Temperature Environments, IEEE Transactions on Device and Materials Reliability (Accessed July 18, 2024)