This letter describes the collector-short technique for improving the blocking capability of the lateral IGBT (LIGBT) on the SOI film. The concept of our proposed techniques is to prevent the injection of the minority carrier from the collector region to the high electric field area. This can be done by replacing the p+-collector layer at the sharp corner of the collector region, where the potential distribution in the device is subject to the diffusion curvature effect of the n-buffer layer, with the n+-collector-short layer. By only introducing the collector-short region to the sharp corner of the collector region, an increase of about 40 V in the breakdown voltage over the LIGBT without the collector-short region can be achieved.

The static and dynamic characteristics of the lateral IGBT on the SOI film when the collector voltage of the IGBT is applied to the substrate are invesigated for its application to the high side switch. The measurements on the blocking capability and the switching characteristics under an inductive load are carried out with varying the thickness of the SOI film. The 260 V IGBT can be fabricated on the 5 µm thick SOI film without the special device structure. It is confirmed that the switching speed depends strongly on the SOI film thickness, not on the substrate bias. The dynamic latch-up current during the turn-off transient increases with the decrease in the SOI film thickness. This is caused by the large transient substrate current. This paper exhibits that applying the collector voltage of the IGBT to the substrate makes it possible to improve the characteristics of the IGBT on the thin SOI film.