SiC vertical double diffused metal-oxide-semiconductor (VDMOS) device and fabrication method thereof

Abstract

The invention discloses a SiC vertical double diffused metal-oxide-semiconductor (VDMOS) device and a fabrication method thereof, and belongs to the technical field of a power semiconductor. A poly-silicon layer is directly deposited on a surface of a junction field-effect transistor (JFET) region of the SiC VDMOS device to form a Si / SiC heterojunction, a diode is further integrated in the device, and the application of the device in the field of an inversion circuit, a chopping circuit and the like is optimized. Compared with the prior art directly employing a VDMOS parasitic SiC diode, the SiC VDMOS device has the advantages of relatively low power loss, relatively fast working speed and relatively high working efficiency, and positive conduction is easier to achieve; compared with the prior art that a fast recovery diode (FRD) is reversely connected with the exterior of the device in parallel, the SiC VDMOS device has the advantages that the usage number of the device is reduced, connection lines between the devices are reduced, and the miniature development of the device is promoted; moreover, the grid width is reduced, the grid capacitance is reduced, and the working speed of the device is further increased; and therefore, the VDMOS device proposed by the invention has wide application prospect in the circuit field of the inversion circuit, the chopping circuit and the like.

Description

technical field [0001] The invention belongs to the technical field of power semiconductors, and in particular relates to a silicon carbide VDMOS device and a manufacturing method thereof. Background technique [0002] Since mankind entered the 21st century, energy issues have become increasingly prominent. Today, as the call for energy saving and emission reduction is getting louder and louder, the problem of electric energy conversion in household appliances, electric vehicles, industrial production, and locomotive traction is particularly important. Researchers in the field of power electronics can optimize and improve the power management system. It seems very important. [0003] Power devices are at the heart of modern power systems. Since the performance of traditional silicon-based power devices is very close to the limit of silicon materials, it is difficult to greatly improve their performance. Therefore, some wide-bandgap semiconductor materials such as silicon ...

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Problems solved by technology

However, the conduction voltage drop of the parasitic silicon carbide diode obtained in this way is large (the conduction voltage drop of the silicon carbide PN junction is about 3V), and the reverse recovery characteristic is poor (the conductance modulation in the drift region injects a large amount of excess load during forward conduction flow), which leads to high power loss, which is contrary to the current application concept emphasizing green environmental protection; at the same time, because of its low working speed, it leads to low working efficiency, which is suitable for the application of silicon carbide VDMOS devices in inverter circuits, chopper circuits, etc. It is extremely unfavorable; the second is: use the device in antiparallel with an external fast recovery diode (FRD)

However, this method will cause an increase in system cost, an increase in volume, and a decrease in reliability due to the increase in metal connections, which ultimately makes the promotion of silicon carbide VDMOS devices in traditional inverter circuits, chopper circuits and other circuit applications limited. a certain obstacle

[0006] In summary, how to realize the wide application of silicon carbide VDMOS devices in inverter circuits, chopper circuits and other circuits, and solve the problems of high power loss, low work efficiency and high system cost in existing applications has become an important issue in this field. Problems that technicians need to solve urgently

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