Separated gate VDMOS device with high reliability and manufacturing method thereof

Abstract

The invention provides a separated gate VDMOS device with high reliability and a manufacturing method thereof. The device comprises a first conductive type substrate, a first conductivity type drift region, a first dielectric oxide layer, a separation gate polycrystalline electrode, a second dielectric oxide layer, a third dielectric oxide layer, a control gate polycrystalline electrode, a secondconductivity type well region, a heavily doped first conductivity type region, a heavily doped second conductivity type region, a source metal contact, a control gate metal contact and a separation gate metal contact. The groove width is increased in the transition region, primary transition region gate polycrystalline etching is added to form a structure that the control gate polycrystal and thegate oxide layer surround the separation gate metal contact, dielectric oxide layer isolation between a control gate and a separation gate required by conventional separation gate leading-out is avoided, the problems of boron absorption and phosphorus discharge caused by thick oxygen isolation and electric field concentration caused by a curvature effect are completely eradicated, the problem of insufficient exhaustion of a transition region during thick oxygen isolation is solved, advanced breakdown of the transition region of the device is eliminated, and the withstand voltage of the deviceis ensured.

Description

technical field [0001] The invention belongs to the field of power semiconductors, and in particular relates to a high-reliability split-gate VDMOS device and a manufacturing method thereof, including a cell region, a transition region and a terminal region. Background technique [0002] Due to its superior characteristics, power devices are widely used in various fields such as mobile communications, automotive electronics, and mobile terminals. Trench VDMOS is one of the most widely used power devices, and its structure has been continuously improved. Among them, the split gate (Split-Gate VDMOS) can increase the doping concentration of the drift region and reduce the on-resistance of the device because the split gate electrode plays the role of longitudinal field plate assisted depletion, and at the same time shields the capacitance between the gate and the drain, with Due to the excellent switching characteristics, it has received extensive attention. How to extract the...

AI Technical Summary

Problems solved by technology

How to extract the split gate without changing the characteristics of the device is a key issue in the design of split gate VDMOS devices. The traditional extraction method often requires a dielectric oxide layer to isolate the control gate and the split gate, and there are often boron absorption and phosphorus removal effects and curvature at the isolation of the oxide layer. The problem of electric field concentration caused by the effect will affect the withstand voltage of the device, which will be more obvious when the concentration of the drift region of the device increases; at the same time, because there is no control gate polycrystalline in the isolated thick oxide layer, there may be insufficient depletion in the transition region, and the same Will affect the device withstand voltage

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