Trench gate MOS power device and gate manufacturing method thereof

Abstract

The invention provides a trench gate MOS power device and a gate manufacturing method thereof. Two kinds of gate oxide layers with different thicknesses are formed at different positions through two times of thermal oxidation processes. Due to the arrangement of the thin oxide layer, the threshold voltage can meet the normal working requirement of the trench gate MOS power device, so the normal switching action of the MOS power device is guaranteed;the thick oxide layer can reduce Miller capacitance, so the problem that switching behaviors are difficult to adjust and control is solved, andtheswitching loss is reduced;the thick oxide layer is high in carrier bombardment resistance, so thelong-range reliability of the whole device is improved. According to the invention, the Miller capacitance is reduced while the normal switching action of the MOS power device is ensured, the problem that the switching behavior is difficult to regulate and control is solved, the switching loss is reduced, the long-range reliability is improved, and the method is not limited by the threshold voltage.

Description

technical field [0001] The invention belongs to the field of semiconductors, and in particular relates to a trench gate MOS power device and a gate fabrication method thereof. Background technique [0002] The gate oxide layer of a conventional trench gate MOS (Metal Oxide Semiconductor) power device is formed by single thermal oxygen. Due to the limitation of threshold voltage, the thickness of thermal oxide layer usually cannot be too thick, i.e. the gate oxide layer capacitance C OX larger. The Miller capacitance of the device can be expressed as: [0003] [0004] Gate Oxide Capacitance C OX larger, the Miller capacitance C Miller high, so that the switching behavior is difficult to control and the switching loss is difficult to reduce. At the same time, since the bottom of the trench is usually a high electric field region, carriers are bombarded and injected into the gate oxide layer at the bottom of the trench during the transport process, thus affecting the l...

AI Technical Summary

Problems solved by technology

[0005] In order to solve the high Miller capacitance of trench gate MOS power devices in the prior art, it is difficult to control the switching behavior and reduce the switching loss; the carrier bombards the gate oxide layer and affects the long-term reliability of the gate and the entire device. Problem, the present invention provides a trench gate MOS power device and its gate manufacturing method, the specific scheme is as follows:

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