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 invention overcomes the adverse effects of the N-type charge storage layer in the traditional structure and obtains more excellent voltage resistance performance. Compared with the traditional method, it solves the problem of deepening the trench gate depth and reducing the unit cell width, which causes the switching performance of the device. , conduction voltage drop and switching loss compromise characteristics and reliability impairment issues. By introducing a series diode structure into the P-type body region, the present invention clamps the channel voltage of the MOSFET to a very small value, thereby reducing the saturation current density of the device and improving the short-circuit safe operating area of ​​the device; The introduction of split electrodes and split electrode dielectric layers into the gate structure improves the switching performance of the device while ensuring the threshold voltage and switching speed of the device; the floating P-type body region improves the compromise characteristics of the forward conduction voltage drop and switching loss of the device . In addition, the present invention proposes that the manufacturing process of the CSTBT device is compatible with the traditional manufacturing process.

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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