Deep trench MOSFET terminal structure and preparation method thereof

Abstract

The invention provides a deep trench MOSFET terminal structure and a preparation method thereof. The deep trench MOSFET terminal structure comprises a substrate of a first conductive type; an epitaxial layer of a first conductivity type; a plurality of first trenches; a first dielectric layer; a first source polysilicon layer; a first well region of a second conductivity type; a plurality of second trenches; a second dielectric layer; a second source polysilicon layer; a gate polysilicon layer; a gate oxide layer and an insulating isolation layer. According to the deep-groove MOSFET terminal structure, the first well region of the second conduction type is arranged at the bottom of the first groove of the terminal protection region to serve as a JTE structure, so that an electric field at the bottom of the first groove is dispersed, a longitudinal electric field transversely extends in the terminal protection region, the voltage withstanding characteristic of the deep-groove MOSFET terminal structure is effectively improved, the withstand voltage of the terminal protection area is higher than that of the active area and is not limited by the withstand voltage of the active area, and terminal protection can be effectively carried out.

Description

technical field [0001] The invention belongs to the technical field of integrated circuit design and manufacture, and in particular relates to a deep trench MOSFET terminal structure and a preparation method thereof. Background technique [0002] In the design of power semiconductor devices, the design of the terminal protection area is very important. The design of the active area determines the characteristics of the resistance, capacitance and breakdown voltage of the power semiconductor device, but it is limited by the effectiveness and area of ​​the terminal protection design. In a good terminal design, in order to ensure reliability during the period, the voltage breakdown point should fall in the active area instead of the terminal protection area. At the same time, the area occupied by the terminal protection area will directly affect the on-resistance of the active area. [0003] Because the performance of deep trench devices is better than that of traditional tren...

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Problems solved by technology

[0005] In view of the above-mentioned shortcomings of the prior art, the purpose of the present invention is to provide a deep trench MOSFET terminal structure and its preparation method, which is used to solve the problem that the withstand voltage of the terminal protection area of ​​the MOSFET terminal device in the prior art is lower than the existing one. The withstand voltage of the source region limits the overall withstand voltage of the device, resulting in high on-resistance and reduced reliability of the device design.

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