Evaluation of planar and trench IGBT for hard- and soft-switching performance

This paper presents a comparison of planar and trench IGBT in hard and soft-switching applications. Higher carrier density in trench IGBTs results in smaller cell size and improved conduction. It is shown that this increase in the concentration of excess charges also results in inferior turn-off performance. Hard-switching performance is dominated by turnoff losses. The trench IGBT under study has higher switching losses than identically rated planar IGBT. Soft switching results in significant reduction of the turn-off stress; thus promising an increase in switching frequency till the device becomes the limiting factor once again. High switching losses of trench IGBTs may be a setback from this consideration even as conduction performance of the device improves significantly. It is also shown that electrothermal consideration can significantly limit the short circuit withstanding capability of trench IGBTs in comparison with planar IGBT.