Modeling for Internal Transparent Collector IGBT

摘要

Internal transparent collector (ITC) insulated gate bipolar transistor (IGBT) is a new type IGBT. Its structure is quite similar to that of the PT-IGBT, but a very low carrier lifetime control region (LCLCR) is introduced in the collector region near the p-collector/n-buffer junction. In this paper, an analysis model for ITC-IGBT is proposed. The collector current density is given. It is function of carrier injected level, device physical parameters (carrier diffusion coefficient, diffusion length), and technology parameters (Doping level, base width, and position of LCLCR). The influence of the position of LCLCR, as well as carrier lifetime in it, on device's characteristics are discussed. For certain current density, if carrier lifetime in LCLCR is less than 0.01ns, and LCLCR is localized at 0.9μm away from base/collector junction, hole injection level decreases with temperature. Considering the mobility also decreases with temperature, device's on-state voltage VON will have positive temperature coefficient. The device is rugged; If carrier lifetime in LCLCR is about 1ns, and LCLCR is just under base/collector junction, the hole injection level increase with temperature. Even if the mobility's decrease with temperature can not compensate the reduction of VON, the decrease degree of VON is much less than that of PT-IGBT. The device is more rugged than PT-IGBT. Optimum the position and carrier lifetime of LCLCR can make the device either rugged or less temperature sensitive (VON increase little with temperature). The position and carrier lifetime of LCLCR also plays important role for device's turn-off feature. When the position of LCLCR is settled, the lower carrier lifetime in LCLCR is, the shorter falling time will be. But when carrier lifetime in LCLCR is less than 10ps, the falling time is seldom influenced by the carrier lifetime in LCLCR. Further reduction of turn-off time can be obtained by reducing the distance of LCLCR to the collector/base junction.