A novel structure of LIGBT with 3D RESURF junction and segmented-anode-segmented-cathode

In this paper a novel SOI LIGBT with a symmetric-separated-anode to improve the latch-up susceptibility and simultaneously maintain a good transient response without jeopardizing the blocking capability is proposed. This structure contains segmented-anode and segmented-cathode (SASC), channeling hole-current directly into P⁺ emitter without flowing underneath the N⁺ diffusion. The anode configuration is symmetric and separated in order to direct straight the electron-current to reach the anode side in on-state. Based on 3D RESURF principle, we propose an integrated structure consisting of a freewheeling PIN diode in parallel with LIGBT to improve the blocking voltage of LIGBT. The PIN diode provides a transversal junction to the drift region of LIGBT resulting in a higher breakdown voltage. Furthermore, the p-base region of the segmented-cathode in the PIN diode part is extended to provide a bypass path for the hole-current so that the latch-up current density is increased. The switching time can also be reduced thanks to the SASC characteristics. Both of the two devices proposed in this paper can be implemented by utilizing BCD process on the SOI substrate.