Groove-shaped insulated gate bipolar transistor and fabrication method thereof

Abstract

A groove-shaped insulated gate bipolar transistor and a fabrication method thereof belong to the technical field of power semiconductors. A cell structure of a second conductive type of channel MOSFETis introduced to a second conductive type of floating region of the groove-shaped insulated gate bipolar transistor, and a gate electrode and a drain of the MOSFET are circuit-shorted with a zero potential; since the potential of the floating region is raised to be higher, the potential of a first conductive type of semiconductor base region is also raised when a device is cutoff, the MOSFET is started after the potential is larger than a threshold voltage of the MOSFET, holes flow out of the drain from a surface channel of the MOSFET, so that the hole extraction speed is accelerated, the cutoff time and the cutoff loss are reduced, and the compromise characteristic of the positive conduction and the cutoff loss is improved. Moreover, the invention also relates to the fabrication method of the groove-shaped insulated gate bipolar transistor. The fabrication process is simple and controllable and is highly compatible with an existing process.

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 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 turned off, the turn-off time is increased, thereby increasing the turn-off loss Eoff, The tradeoff between Vce and Eoff deteriorates

like figure 2 As shown, in order to speed up the extraction of excess carriers in the drift region 8 of the semiconductor of the first conductivity type during shutdown, the floating region 15 of the second conductivity type is connected to the emitter metal 4 of the device, so that the excess current carrying The electrons can be extracted through the floating region 15 of the second conductivity type, which reduces the turn-off time and the turn-off loss Eoff. However, when the device is conducting forward, a part of holes flow into the floating region 15 of the second conductivity type, and The outflow from the upper emitter metal 4 weakens the conductance modulation of the drift region, which increases Vce, and the compromise between Vce and Eoff will also deteriorate

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