Method and device for improving surface mobility of silicon carbide lateral double-diffusion field effect transistor

Abstract

The invention discloses a method and device for improving the surface mobility of a silicon carbide lateral double-diffusion field effect transistor. The method comprises the steps: introducing a voltage bias tube, enabling the surface electron concentration of a drift region to be increased when a silicon carbide LDMOS is in forward conduction, enabling the probability that a single electron is captured by a surface trap of an oxide layer above the drift region to be reduced, and enabling the electron mobility to be improved. The device comprises a P-type substrate, which is provided with a P-type isolation layer which divides the device into an LDMOS and a voltage bias tube, the LDMOS comprises a first N-type drift region, a first source region, a first drain region, a gate oxide layer and a polysilicon gate, and is characterized in that four polysilicon field plates which are separated from one another are arranged on the gate oxide layer, the voltage bias tube comprises a second N-type drift region, a second source region and a second drain region, four N+ injection layers are arranged in the second N-type drift region, the polysilicon gate is connected with the second source region, the first drain region is connected with the second drain region, and the four polysilicon field plates are respectively connected with the four N+ injection layers.

Description

technical field [0001] The present invention mainly relates to the technical field of wide-bandgap power semiconductor devices, in particular to a method and device for improving the surface mobility of silicon carbide lateral double-diffusion field effect transistors, which are suitable for many power control and processing fields such as switching power supplies and inverters. In order to reduce the on-state loss of the device in the case of forward conduction. Background technique [0002] Double-diffused MOSFET (DMOS) has the characteristics of high current, high voltage resistance, and high switching speed. It is widely used in the fields of switching power supply, household appliances, smart grid and traffic transmission. There are two main types of DMOS, VDMOSFET (VerticalDouble-diffused MOSFET) and LDMOSFET (LateralDouble-diffused MOSFET), among which LDMOS is easier to compare with CMOS Process compatible applications are more extensive. [0003] In recent years,...

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Problems solved by technology

However, since the current path of SiC LDMOS is under the oxide layer, the surface traps in the oxide layer will reduce the mobility of carriers and affect the transport of carriers. Therefore, the conventional SiC LDMOS has a high on-resistance, positive Poor conduction characteristics

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