Back surface structure of reverse conducting IGBT and manufacturing method thereof

Abstract

The invention discloses a back surface structure of a reverse conducting IGBT. The back surface structure includes a drift region, a first N+ buffer layer, an insulating layer, a P+ collector region, an N+ short circuit region and a collector electrode metal layer. The P+ collector region is separated from the N+ short circuit region by the drift region in the middle. A depleted part of the N+ short circuit region is connected to the collector electrode metal layer via the insulating layer, and the rest is directly connected to the collector electrode metal layer. The back surface structure and a manufacturing method thereof provided by the utility model add the low-doped drift region of an N- region between the P+ collector region and the N+ short circuit region, so that the P+ collector region is more positively biased, and thus rebounding phenomena are avoided. Besides, the back structure can increase the effective conducting area of the P+ collector region and the total injection of a cavity, reduces conductive voltage drop, and thus reduces power consumption.

Description

technical field [0001] The invention relates to the technical field of power semiconductor devices, in particular to a back structure of a reverse conduction type IGBT and a preparation method thereof. Background technique [0002] The reverse conduction IGBT is a new type of power device, which has many advantages but also introduces some disadvantages, such as bounce phenomenon. [0003] By comparison, it can be found that most of the structure of the reverse conduction IGBT is similar to that of the traditional IGBT. The biggest difference is that the collector of the reverse conduction IGBT is not a continuous P + area, but intermittently introduce some N + short circuit area. [0004] P of the reverse conduction IGBT - base area, N - Drift zone, N + buffer layer and N + The shorted area forms a PIN diode. The reverse conduction IGBT is equivalent to an IGBT and a PIN diode in antiparallel connection, but it is realized on the same chip. When the IGBT is under r...

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Problems solved by technology

[0007] A reverse conduction type IGBT is also disclosed in the prior art, and the current distribution during forward conduction is as follows: figure 2 As shown, although the bounce phenomenon can be effectively eliminated, but due to the P + Collector area 1 and N + Shorted area 2 is directly adjacent, resulting in part P + Collector region 1 fails to conduct, making P + The hole injection efficiency in the collector region 1 is reduced, which will indirectly waste the utilization rate of the chip and increase the manufacturing cost

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