Unipolar Conductivity Enhancement and Its Experiments in SOI-LIGBT

A novel 850-V silicon-on-insulator (SOI) lateral insulated gate bipolar transistor with unipolar conductivity enhancement (UE LIGBT) is proposed and experimentally realized in this article. A thick SOI region with charge-balanced n- and p-pillars is introduced near the cathode of the UE LIGBT to enhance the conductivity by high concentration charge-balanced majority carriers. A normalized conductivity factor $\eta _{\text {c}}$ is proposed to evaluate the conductivity enhancement of the new device, based on which the unipolar conductivity region is optimized to reduce the ON-state voltage drop ${V}_{ \mathrm{\scriptscriptstyle ON}}$ while keeping the similar turn-off loss and breakdown voltage ${V}_{\text {B}}$ . The experiments demonstrated that ${V}_{ \mathrm{\scriptscriptstyle ON}}$ and conduction capability of the UE LIGBT are improved by 16.7% and 38.9% when compared with the conventional LIGBT (Con LIGBT) under the same breakdown voltage ${V}_{\text {B}}$ of 850 V.