A trench gate charge storage type insulated gate bipolar transistor and its manufacturing method

Abstract

A trench gate charge storage type insulated gate bipolar transistor and a manufacturing method thereof belong to the field of semiconductor power devices. The present invention introduces a trench emitter structure into the N-type drift region of the traditional CSTBT device structure, and sequentially introduces a P-type layer and a series diode structure under the trench emitter structure and on the surface, and also has the function of partially penetrating in the vertical direction The groove gate structure in the N-type charge storage layer, through the above-mentioned improvement, the present invention solves the problem that there is a contradictory relationship between the forward conduction performance and the withstand voltage performance of the device caused by increasing the doping concentration of the N-type charge storage layer in the traditional CSTBT device ; The saturation current density of the device is reduced, and the short-circuit safe working area of ​​the device is improved; the switching speed of the device is increased, and the switching loss is reduced; the breakdown voltage of the device is increased, and the reliability is improved; the forward voltage is optimized The compromise between drop and turn-off loss; at the same time, the manufacturing method of the device of the present invention is compatible with the manufacturing process of the existing CSTBT device.

Description

technical field [0001] The invention belongs to the technical field of semiconductor power devices, in particular to an insulated gate bipolar transistor (IGBT), in particular to a trench gate charge storage type insulated gate bipolar transistor (CSTBT). Background technique [0002] Insulated gate bipolar transistor (IGBT), as one of the core electronic components in modern power electronic circuits, is widely used in various fields such as transportation, communication, household appliances, and aerospace. Insulated gate bipolar transistor (IGBT) is a new type of power electronic device composed of an insulated field effect transistor (MOSFET) and a bipolar junction transistor (BJT), which can be equivalent to a MOSFET driven by a bipolar junction transistor. . IGBT combines the working mechanism of MOSFET structure and bipolar junction transistor. It not only has the advantages of MOSFET easy to drive, low input impedance, and fast switching speed, but also has the adva...

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Problems solved by technology

[0005] The implementation of method (1) will increase the gate-emitter capacitance and gate-collector capacitance at the same time, and the switching process of the IGBT is essentially the process of charging / discharging the gate capacitance, so the increase in the gate capacitance will Makes the charging / discharging time longer, which in turn causes the switching speed to decrease

Therefore, the deep trench gate depth will reduce the switching speed of the device, increase the switching loss of the device, and affect the compromise characteristics of the device's conduction voltage drop and switching loss; and the implementation of method (2) will increase the device's switching loss The gate capacitance will reduce the switching speed of the device and increase the switching loss, which will affect the compromise between the conduction voltage drop and switching loss of the device. On the other hand, the large channel density will also increase the saturation current density of the device, making the device short-circuit safe. work area deterioration

In addition, the gate oxide layer in the trench gate structure is formed in the trench by one thermal oxidation. In order to ensure a certain threshold voltage, the thickness of the entire gate oxide layer is required to be small. However, the MOS capacitance and the thickness of the oxide layer Inversely proportional, which makes the thin gate oxide thickness in traditional CSTBT devices will significantly increase the gate capacitance of the device, and the electric field concentration effect at the bottom of the trench will reduce the breakdown voltage of the device, resulting in poor reliability of the device

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