Switching Loss Reduction in Superjunction IGBTs via Analysis of Vertical Charge Imbalance

This study investigates the switching loss reduction mechanisms in 1.2 kV-class Tapered and protruded pillar Super Junction Insulated Gate Bipolar Transistors (T-SJ IGBTs). Experimental results at 150°C demonstrate a 61.8% reduction in turn-off energy loss $\left(E_{\text{off}}\right)$ by increasing $\mathrm{d} V_{\text{CE}} / \mathrm{d} t$ from $5.8 \text{kV} / \mu \mathrm{s}$ to 18.9 $\text{kV} / \mu \mathrm{s}$, and a 12.9% reduction in turn-on energy loss $(E_{\mathrm{o}\mathrm{n}})$ under identical dIC/dt condition. The reduction in switching loss is closely linked to the optimization of doping concentrations in the p- and n-pillars, with the net charge gradient playing a key role. The net charge can be expressed as a deviation from the ideal vertical SJ (VSJ) structure, and its gradient strongly influences d $V_{\text{CE}} / \mathrm{d} t$ and $E_{\mathrm{o}\text{ff}}$.