Trench MOSFET with charge balance structure and manufacturing method thereof

Abstract

The invention discloses a trench MOSFET with a charge balance structure and a manufacturing method thereof. The trench MOSFET comprises a substrate with a first conduction type, the upper side of the substrate is subjected to epitaxial growth, the middle part of the epitaxy is etched to form a first groove, a connecting layer of the first conduction type grows on the surface of the first groove, a column region of a second conduction type is formed in the first groove on the inner side of the connecting layer through epitaxial growth; the epitaxy on the two sides of the first groove is etched to form a second groove; and an oxide layer grows on the surface of the second groove, and a high-K dielectric layer grows on the upper surface of the oxide layer. A charge balance structure is formed in the first groove, a parallel electric field is introduced, electric field distribution of a drift region is changed, device withstand voltage is improved, Rsp (specific resistance per unit area) is reduced, so that conduction loss is reduced, a high-K dielectric material is adopted in the second groove, the restraining effect of the second deep groove on BVDSS can be optimized, the device performance is further optimized, the device is compatible with an existing process platform, and the process is simple to implement and enough in process window.

Description

technical field [0001] The invention relates to the technical field of a trench MOSFET with a charge balance structure and a manufacturing method thereof, in particular to a trench MOSFET with a charge balance structure and a manufacturing method thereof. Background technique [0002] Ordinary trench MOSFET products mainly rely on the drift region to withstand the withstand voltage. Generally, the width of the drift region is increased by increasing the epitaxial resistivity and thickness to increase the breakdown voltage (BVDSS). Correspondingly, the on-resistance (Rdson) of the device will also increase. Rapidly increasing, Rdson and BVDSS have a 2.5-fold restrictive relationship. [0003] Although the trench MOSFET introduces a lateral electric field in the drift region, the constraint relationship between Rdson and BVDSS can be improved. However, due to the limitations of the gate oxide layer and the input capacitance (Ciss), combined with the difficulty of the process,...

AI Technical Summary

Problems solved by technology

However, due to the limitation of the gate oxide layer and the input capacitance (Ciss), combined with the difficulty of the process, the trench depth cannot be increased infinitely

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