SiC VDMOS (vertical double-diffused metal oxide semiconductor) device

Abstract

The invention belongs to the technical field of semiconductors, and particularly relates to an SiC VDMOS (vertical double-diffused metal oxide semiconductor) device. According to the composite gate dielectric structure provided by the SiC VDMOS device, a high dielectric constant gate dielectric / SiO2 stack structure is adopted above a channel, the part above a JFET (junction field-effect transistor) region adopts SiO2 completely, and total physical thicknesses of gate dielectrics above the channel and the JFET region are equal. When the device is in a forward on state, physical thicknesses of the gate dielectrics can be increased when high dielectric constant materials are introduced in the gate dielectrics, so that the electric field intensity of the gate dielectrics can be reduced, and meanwhile, threshold voltage cannot be increased; when the device is in an off state, the maximum surface electric field intensity position is located in the JFET region, the thick SiO2 above the region can decrease the maximum value of the surface electric field, and accordingly, the electric field intensity of the SiO2 can be reduced. The FN tunneling current of the SiC VDMOS device is reduced by reducing the electric field intensity of the gate dielectrics, and the reliability of a gate oxide is effectively improved.

Description

technical field [0001] The invention belongs to the technical field of semiconductors, and in particular relates to a silicon carbide VDMOS device. Background technique [0002] Silicon carbide (SiC) has the characteristics of large band gap, high critical breakdown electric field, high thermal conductivity and high electron saturation drift velocity, so it has very broad application prospects in the field of high-power, high-temperature and high-frequency power electronics. Among field effect transistors based on SiC, vertical double diffused metal oxide semiconductor field effect transistor (VDMOS) is one of the widely researched objects. [0003] Compared with other wide-bandgap semiconductor materials (such as GaN), SiC has a very obvious advantage that it can directly form SiO through thermal growth. 2 (silicon dioxide), which allows silicon carbide devices to easily inherit the MOS (metal oxide semiconductor) structure and related technologies that have been widely us...

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Problems solved by technology

In this way, the physical thickness of the gate dielectric can be increased without reducing the carrier barrier height at the interface, so the purpose of reducing the FN tunneling current can be achieved, but the SiO in this gate structure 2 Usually very thin, when the VDMOS device breaks down reversely, a large electric field will still be generated on the surface of the JFET region, where the surface gate dielectric is likely to break down in advance

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