Trench type insulated gate bipolar transistor and preparation method thereof

Abstract

The invention relates to a trench type insulated gate bipolar transistor and a preparation method thereof, belonging to the technical field of power semiconductors. A first conductive trench MOSFET isintroduced in a second conductive floating zone of a trench type insulated gate bipolar transistor, a gate electrode of the MOSFET is in short circuit with current conversion metal, so that when thedevice is conducted forwardly, the MOSFET turns off due to low electric potential of the floating zone, electronic current converted by the conversion metal cannot flow out of a leakage electrode through MOSFET, so as not to increase voltage drop of forward conducting; when the device is turned off, MOSFET surface trench electron inverses so as to form an electron flow path due to very high electric potential of the floating zone, so that electron current converted from hole current by the conversion metal can flow out of the leakage electrode through MOSFET, surplus carriers are extracted atfaster speed, off time is shortened and off loss is reduced, and forward conducting and off loss are further balanced. The invention further relates to a preparation method for the trench type insulated gate bipolar transistor.

Description

technical field [0001] The invention belongs to the technical field of power semiconductors, and in particular relates to a trench type insulated gate bipolar transistor and a preparation method thereof. Background technique [0002] Insulated Gate Bipolar Transistor (IGBT) is a bipolar device controlled by an insulated gate. The higher the non-equilibrium carrier concentration in the body, the more significant the conductance modulation effect and the higher the current density. figure 1 It shows a half-cell structure of a traditional trench type IGBT device. When the device is in forward conduction, due to the existence of the floating region 15 of the second conductivity type, it will increase the current carrying capacity on the side of the emitter when it is in forward conduction. Subconcentration reduces the turn-on voltage drop, but because a large amount of excess carriers cannot be extracted through the second conductivity type floating region 15 when the IGBT is tu...

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Problems solved by technology

Figure 1 shows a traditional trench IGBT device When the device is in forward conduction, due to the existence of the floating region 15 of the second conductivity type, when it is in forward conduction, it will increase the carrier concentration on the side of the emitter and reduce the conduction voltage drop. However, when the IGBT is turned off, a large amount of excess carriers cannot be extracted through the floating region 15 of the second conductivity type, which increases the turn-off time, thereby increasing the turn-off loss Eoff, and the compromise between Vce and Eoff is deteriorated.

As shown in Figure 2, in order to speed up shutdown The extraction of excess carriers in the drift region 8 of the semiconductor of the first conductivity type connects the floating region 15 of the second conductivity type to the emitter metal 4 of the device, so that when it is turned off, the excess carriers can float through the second conductivity type region 15, which reduces the turn-off time and the turn-off loss Eoff, but when the device is in forward conduction, a part of holes flow into the second conductivity type floating region 15 and flow out from the emitter metal 4 above it , which weakens the conductance modulation in the drift region, making Vce increase, and the compromise between Vce and Eoff will also deteriorate

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