Cell Design Consideration in SiC Planar IGBT and Proposal of New SiC IGBT With Improved Performance Trade-Off

Abstract

In silicon carbide (SiC) planar insulated-gate bipolar transistor (IGBT), a large distance between neighboring p-bodies is beneficial to enhance the on-state conductivity modulation, but will expose the gate oxide to high electric field in off-state. With p-bodies placed closer, the gate oxide field is reduced, but the conductivity modulation is suppressed. In this work, a new SiC planar IGBT with oxide shield is proposed and studied by TCAD simulations. The proposed SiC IGBT achieves improved trade-off between on-state voltage drop $(V_{\mathrm{ ON}})$ and maximum gate oxide electric field $(E_{\text {ox-m}})$ . When a quite larger distance between neighboring p-bodies is adopted in the proposed SiC IGBT, a low $V_{\mathrm{ ON}}$ is obtained, while the $E_{\text {ox-m}}$ can be kept at a small value with the oxide shielding structures protecting the gate oxide. Switching characteristics are also studied, and the proposed SiC-IGBT delivers much better trade-off between turn-off energy loss $(E_{\mathrm{ OFF}})$ and $V_{\mathrm{ ON}}$ than the conventional SiC planar IGBT.

Keywords

• SiC IGBT
• oxide shield
• on-state voltage drop
• maximum gate oxide electric field
• turn-off energy loss