Latch-up resistant igbt with variable composition mixed crystal emitter

Abstract

An anti-latch IGBT with variable composition mixed crystal emitting regions belongs to the technical field of power semiconductor devices. The invention is based on the conventional IGBT structure, by changing the pure silicon material in the emitter region into a mixed crystal with gradually changing composition, so as to form an energy band structure of the emitter region with a gradually changing forbidden band width. Under the premise of not reducing the built-in potential of the PN junction formed by the emitter region and the base region, the energy band structure forms an accelerating electric field for the minority carriers in the emitter region, thereby increasing the minority carrier diffusion current density in the emitter region, and the base region to The implantation of the emitter region is enhanced; on the other hand, the implantation of the emitter region into the base region remains unchanged. Therefore, the injection efficiency of the emitter junction of the parasitic transistor composed of the emitter region, the base region and the drift region is reduced, and the current amplification factor is reduced, making it more difficult for the parasitic thyristor in the IGBT to reach the latch-up condition, which increases the critical latch-up current of the IGBT. The safe working area of ​​the IGBT is increased, and the reliability of the IGBT is improved.

Description

technical field [0001] The invention belongs to the technical field of power semiconductors and relates to an IGBT device with good anti-latch performance. Background technique [0002] IGBT is a representative type of power semiconductor device, because it has the advantages of high withstand voltage, low on-resistance, easy driving, fast switching speed, etc. There are important applications in the field. Latch-up problem is one of the important reasons that threaten the reliability of IGBT. [0003] The basic IGBT structure and its equivalent circuit are shown in Figure 1.1 and Figure 1.2. It can be seen from Figure 1.1 that the IGBT structure includes an N+ emitter region 3, a P-type base region 6, an N-drift region 10 and a P+ collector. The region 12 constitutes an N-P-N-P four-layer three-junction thyristor structure 14 . The mechanism of IGBT latch-up is explained by the equivalent circuit in Figure 1.2: when the IGBT is working normally, the parasitic thyristor 1...

AI Technical Summary

Problems solved by technology

However, these two methods will reduce the forward conduction voltage drop of the NPN emitter junction PN junction, the PN junction is easy to be forward biased, and the parasitic NPN transistor is easy to open, which is not good for improving the anti-latch-up ability of the IGBT

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