Longitudinal double-diffused metal oxide semiconductor field effect transistor with composite dielectric layer wide bandgap semiconductor and manufacturing method thereof

Abstract

The invention provides a broad-band gap semiconductor vertical double diffusion metal oxide semiconductor field effect transistor having a composite dielectric layer and a manufacturing method thereof. The device is characterized in that the composite dielectric layer is formed by a semi-insulation polysilicon layer (SIPOS) and a high dielectric constant (High K) dielectric layer at a drift region side wall below a device gate electrode. When the device is turned off, the SIPOS column and the High K dielectric layer have uniform electric fields, electric distribution in the drift region of the device is made to be uniform through electric field modulation, moreover, exhaust of the drift region is commonly facilitated by the SIPOS column and the High K dielectric layer, exhaust capability of the device drift region is substantially improved, drift region doping concentration of the device is made to increase, and conduction resistance is reduced; when the device is turned on, the side wall of the drift region has multiple carrier accumulation layers, and conduction resistance of the device is reduced further.

Description

technical field [0001] The invention relates to the field of semiconductor devices, in particular to a trench (Trench) type vertical double-diffused metal oxide semiconductor field effect transistor. Background technique [0002] Wide bandgap semiconductor materials have the characteristics of large band gap, high critical breakdown electric field, high thermal conductivity and high electron saturation drift velocity, so they have very broad application prospects in the field of high-power, high-temperature and high-frequency power electronics. At present, among the field effect transistors based on SiC, a typical wide-bandgap semiconductor, the vertical double-diffused metal-oxide-semiconductor field effect transistor (VDMOS) is one of the widely studied objects. In 1985, a trench (Trench) MOS structure was proposed by D.Ueda et al. The U-shaped groove structure makes the conduction channel of the device change from horizontal to vertical, which effectively eliminates the ...

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Problems solved by technology

However, in the field of high-voltage applications of power devices, as the breakdown voltage of the device increases, the thickness of the power VDMOS epitaxial layer increases continuously, and the doping concentration of the drift region gradually decreases, resulting in the on-resistance of the device decreasing with the increase of the breakdown voltage of the device. increases, making the conduction loss of the device increase

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