Trench-gate charge storage type IGBT and manufacturing method therefor

Abstract

The invention discloses a trench-gate charge storage type IGBT and a manufacturing method therefor, and belongs to the technical field of semiconductor power devices. A trench-gate emitter structure connected with a P-type volume region is introduced to an N-type drift region at one side of a trench gate in a conventional CSTBT device, thereby enabling the gate-collector capacitance into gate-emitter capacitance, and improving the adverse effect of Miller capacitance. A thick dielectric layer of the trench-gate emitter structure avoids an electric field concentration effect at the bottom of atrench, and improves the breakdown voltage of a device. The depth of a gate electrode is enabled to be less than the junction depth of an N-type charge storage layer, thereby reducing the overall gatecapacitance under the condition that the connection of an IGBT is not affected, improving the switching speed of the device, reducing the switching loss of the device, and improving the compromise characteristics between a positive conduction voltage and the switching-off loss. According to the invention, the existing of the P-type volume region can reduce the extraction area of a hole, and improves the carrier concentration distribution of the whole N-type drift region. Moreover, the noise impact is reduced, and the EMI effect is avoided.

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 IGBT and a manufacturing method thereof. 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 advant...

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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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