A trench gate charge storage type igbt device with clamping structure and its manufacturing method

Abstract

A trench gate charge storage type IGBT device with a clamping structure and a manufacturing method thereof belong to the field of semiconductor power devices. In the present invention, a clamping electrode connected with the emitter metal through a series diode structure is introduced under the gate electrode in the device trench, and a P-type layer connected thereto is arranged under the clamping electrode. The invention can effectively shield the adverse effect of the increase of the doping concentration of the N-type charge storage layer on the withstand voltage performance of the device, overcome the contradiction between the forward conduction and the withstand voltage of the traditional CSTBT structure; reduce the saturation current density of the device, and improve the short circuit of the device Safe working area; increase the switching speed of the device and reduce the switching loss of the device; at the same time, no negative differential capacitance effect will be formed during the dynamic process of turning on, which can effectively avoid current, voltage oscillation and EMI problems during the dynamic process of turning on, and improve the device’s performance. Reliability; improve the electric field concentration effect at the bottom of the trench, and increase the breakdown voltage of the 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) with a clamping structure and its manufacture method. 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 impe...

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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, it will also increase the saturation current density of the device and make the short-circuit safe working area of ​​the device worse.

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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