Silicon carbide MOS device with majority carrier diode

Abstract

The invention provides a silicon carbide MOS device with a majority carrier diode. When the MOS device is turned off, the majority carrier diode is connected in parallel with a PN junction diode, andmeanwhile, on the basis of the characteristics of the low opening voltage and single-polarity current conduction of the majority carrier diode and the large breakover current and high voltage resistance of the PN junction diode, the conduction loss of the device during reverse follow current is reduced, the reverse follow current capability and breakdown voltage of the device are improved, the reverse recovery charges of the device are reduced, and the reliability and integration of the silicon carbide MOS device are improved. When the silicon carbide MOS device is turned on, in order to reduce on resistance, the conduction loss of the MOS transistor is reduced. According to the silicon carbide MOS device of the invention, a current reinforcing injection region is additionally arranged inan active region, and the problem of excessively large JFET resistance due to excessively low epitaxial doping concentration can be solved.

Description

technical field [0001] The invention belongs to the field of semiconductors, in particular to a silicon carbide MOS device with a majority carrier diode. Background technique [0002] Silicon carbide (SiC) is currently the fastest-growing wide-bandgap power semiconductor material. MOS field-effect transistor power devices made of silicon carbide materials can withstand higher voltages and faster switching speeds than Si devices. At present, when the MOS device is turned off, the parasitic body diode in the silicon carbide field effect transistor has a large turn-on voltage, which makes the conduction loss of the MOS device become higher in the freewheeling application process. Therefore, the use of integrated majority carrier diodes in SiC MOS devices can solve this problem. In the prior art, there has been a method of using a Schottky diode as a parasitic body diode to reduce the turn-on voltage, but this method also has defects. First of all, the reverse leakage of the S...

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Problems solved by technology

First of all, the reverse leakage of the Schottky diode is large. If the area occupied by the parasitic Schottky diode is too large during device design, it will affect the reverse breakdown voltage of the MOS device.

Secondly, the voltage drop of the Schottky diode itself is too large when the current is high, which will make the voltage drop loss on the Schottky diode very large when the freewheeling current is large.

At the same time, when the MOS device is turned on, due to the low concentration of silicon carbide epitaxial doping, the JFET resistance in the silicon carbide MOS accounts for a large proportion of the total on-resistance, which increases the conduction loss of the MOS device.

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