SiC vertical double diffusion metal oxide semiconductor structure (VDMOS) device with composite gate dielectric structure

Abstract

The invention discloses a SiC vertical double diffusion metal oxide semiconductor structure (VDMOS) device with a composite gate dielectric structure, and belongs to the technical field of power semiconductor devices. A thought of differentiating modulation of electric fields is adopted according to difference of intensities of electric fields and difference of defect concentrations of gate dielectrics in different areas, namely, high-k gate dielectrics are adopted in channel regions with high-defect concentration and a low electric field, so that a large quantity of trap states caused by using a SiO2 / SiC interface is avoided; the influence on Fowler-Nordheim (FN) tunneling current is obviously reduced; and meanwhile, because the electric field intensity in a channel injection area is small, the reduction on gate dielectric breakdown voltage caused by small offset of conduction band / valence band is weakened; and moreover, a SiO2 gate dielectric (a junction field-effect transistor (JFET) area is formed in a way of extension and is not subjected to ion injection, the surface quality of the JFET area is good, and the SiO2 / SiC interface state is low) is adopted by the JFET area with low defect concentration and a high electric field, and enough high conduction band offset is supplied by the SiO2 dielectric, so that the ahead breakdown of the gate dielectric is avoided.

Description

technical field [0001] The invention belongs to the technical field of power semiconductor devices, and relates to a double diffused metal oxide semiconductor field effect transistor (DMOS) device structure, in particular to a silicon carbide (SiC) DMOS device with a composite gate dielectric structure. Background technique [0002] Silicon carbide (SiC), as a wide-bandgap semiconductor material that has attracted much attention in recent years, has excellent physical properties such as wide bandgap, high critical breakdown electric field, high thermal conductivity, and high electron saturation drift velocity. High power, high frequency, and strong irradiation fields have broad application prospects. [0003] Compared with gallium nitride (GaN) and other wide-bandgap semiconductor materials, SiC materials can directly generate silicon dioxide (SiO2) through thermal oxidation. 2 ), this advantage makes SiC an ideal material for making high-power MOSFET devices. Conventional...

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Problems solved by technology

However, since there are many defects after surface ion implantation, the SiO in the channel implantation region 2 There are still a large number of trap states at the / SiC interface, which not only reduces the channel mobility, but also a large number of SiC / SiO 2 Interface traps and high-field-induced traps together form FN tunneling current, and this gate structure can only partially alleviate gate dielectric breakdown caused by FN tunneling current

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