Double split trench gate charge storage type rc-igbt and its manufacturing method

Abstract

The invention belongs to the technical field of power semiconductor devices, and in particular relates to a reverse conduction trench gate charge storage type insulated gate bipolar transistor. The present invention improves the switching of the device in the IGBT working mode by introducing a double-split electrode with the same potential as the emitter and a dielectric layer between the double-split electrode and the gate electrode at the bottom and side surfaces of the gate electrode in the trench of the RC-IGBT device The speed improves the carrier concentration distribution of the entire N-type drift region, reducing the switching loss of the device; reducing the saturation current density of the device, improving the short-circuit safe working area of ​​the device, and improving reliability; When the current diode is in the working mode, the reverse freewheeling diode has a low diode conduction voltage drop, and the reverse recovery characteristics of the freewheeling diode are improved; at the same time, the double split trench gate charge storage type IGBT manufacturing method proposed by the present invention does not Additional process steps are required, which is compatible with traditional RC‑IGBT fabrication methods.

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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