Silicon carbide MOSFET device with integrated diode and manufacturing method

Abstract

The invention provides a silicon carbide MOSFET (Metal-Oxide-Semiconductor Field Effect Transistor) device with an integrated diode and a manufacturing method. The device comprises a source ohmic contact region, a drain ohmic contact region, an N + substrate, an N-drift region, a P-type base region, a P + source region, an N + source region, a P-type shielding layer, a shielding layer N + source region, an N-type channel region, a gate dielectric layer and a polysilicon gate. According to the trench type silicon carbide MOSFET device provided by the invention, the chip area is greatly saved in a mode of integrating the diodes in the chip. The N-type channel region is introduced to the bottom of the trench, so that the electron barrier height at the interface of the oxide layer is adjusted, the third quadrant characteristic of the device is remarkably improved, the low third quadrant turn-on voltage is realized, and the bipolar degradation effect is avoided; multiple channels are connected in parallel, so that the forward current capability of the device is improved, and the on-resistance is reduced; and the P-type shielding layer wraps and protects the gate groove, so that the electric field of the gate oxide layer is reduced, and the reliability of the device oxide layer is enhanced.

Description

technical field [0001] The invention belongs to the technical field of power semiconductors, and in particular relates to a trench silicon carbide MOSFET device structure integrating low conduction voltage drop diodes. Background technique [0002] As one of the representatives of the third-generation wide bandgap semiconductor materials, silicon carbide (Silicon Carbide) material has a large bandgap (3.26eV), a high critical breakdown electric field (3MV / cm), and a high thermal conductivity (490W / Mk ) and high electron saturation drift velocity (2×10 7 cm / s) and other characteristics, it has broad application prospects in the fields of high-power, high-temperature and high-frequency power electronics. [0003] As the most widely used unipolar device in silicon carbide power devices, silicon carbide MOSFET has low switching loss and high switching frequency, and is more suitable for high frequency working conditions, coupled with its extremely low on-resistance and excellen...

AI Technical Summary

Problems solved by technology

Since the barrier height of the Schottky contact is lower than that of the ohmic contact, the on-chip integrated Schottky diode can effectively reduce the turn-on voltage of the device, but its reverse characteristics strongly depend on the width of the P+ region and the N+ region Proportion

When the ratio of the width of the P+ region is small, the leakage current of the device increases, the breakdown voltage decreases sharply, and the surge current capability is poor; when the ratio of the width of the P+ region is large, the forward characteristics of the device will be seriously affected

At the same time, the temperature characteristics of the Schottky interface in the junction barrier Schottky diode are poor, resulting in a sharp increase in the leakage current of the device at high temperature

Images