Double split trench gate charge storage-type RC-IGBT and manufacturing method thereof

Abstract

The invention belongs to the technical field of power semiconductor devices, and particularly relates to a reverse conducting trench gate charge storage-type insulated-gate bipolar transistor. Double split electrodes which are equipotential to an emitter and dielectric layers between the double split electrodes and a gate electrode are introduced into the bottom part and the side surfaces of the gate electrode in a trench of an RC-IGBT device, so that the switching speed of the device is improved in the working mode of the IGBT; the switching loss of the device is reduced; the saturation current density of the device is reduced; a short-circuit safe operation area of the device is improved; and the reliability is improved. A reverse free-wheeling diode has a low diode turn-on voltage drop in the working mode of the reverse free-wheeling diode; and the reverse recovery characteristics of the free-wheeling diode are improved. Meanwhile, by the manufacturing method of the double split trench gate charge storage-type RC-IGBT provided by the invention, an additional process step does not need to be added; and the manufacturing method is compatible with a traditional manufacturing method of the RC-IGBT.

Description

technical field [0001] The invention belongs to the technical field of power semiconductor devices, and relates to an insulated gate bipolar transistor (IGBT), in particular to a reverse conduction trench gate charge storage type insulated gate bipolar transistor (RC-CSTBT). Background technique [0002] Insulated Gate Bipolar Transistor (IGBT) is a new type of power electronic device combining MOS field effect and bipolar transistor. It not only has the advantages of easy driving and simple control of MOSFET, but also has the advantages of low conduction voltage of power transistor, large on-state current and small loss. It has become one of the core electronic components in modern power electronic circuits and is widely used in Various fields of the national economy such as communications, energy, transportation, industry, medicine, household appliances and aerospace. The application of IGBT plays an extremely important role in improving the performance of power electroni...

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Problems solved by technology

[0004] However, for the traditional RC-CSTBT device structure, in the forward IGBT mode, due to the presence of a higher doping concentration and a certain thickness of the N-type charge storage layer, the breakdown voltage of the device is significantly reduced. In order to effectively shield the N-type Adverse effects of the charge storage layer To obtain a certain device withstand voltage, it is necessary to adopt: 1) deep trench gate depth, so that the depth of the trench gate is greater than the junction depth of the N-type charge storage layer, but the deep trench gate depth not only increases The larger gate-emitter capacitance also increases the gate-collector capacitance, thus reducing the switching speed of the device, increasing the switching loss of the device, and affecting the compromise between the conduction voltage drop and switching loss of the device characteristics; 2) The small cell width minimizes the distance between the trench gates. However, the high-density trench MOS structure not only increases the gate capacitance of the device, but also reduces the switching speed of the device and increases the The switching loss of the device is increased, which affects the compromise characteristics of the conduction voltage drop and switching loss of the device, and increases the saturation current density of the device, making the short-circuit safe working area of ​​the device worse

In the reverse diode freewheeling mode of operation, due to the existence of the built-in potential of the PN junction formed by the P-type base region 7 and the N-type charge storage layer 8 / N-drift region 9, the forward conduction voltage drop is relatively large, and at the same time due to When the freewheeling diode is turned on, a large number of carriers are injected into the N-drift region 9. The existence of a large number of excess carriers makes the reverse recovery characteristics of the freewheeling diode poor, such as long reverse recovery time and large reverse recovery charge. Wait

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