Method for manufacturing terminal structure of deep-groove super-junction metal oxide semiconductor (MOS) device

Abstract

The invention provides a method for manufacturing a terminal structure for a deep trench superjunction MOS device, which includes the steps of: providing a silicon substrate, on which deep trenches with a superjunction structure and a terminal structure are respectively formed; and depositing a third layer in the deep trench. A polysilicon layer, the doping type of the first polysilicon layer is opposite to that of the silicon substrate; the doping impurities in the first polysilicon layer are diffused into the silicon substrate to form an impurity diffusion area around the deep trench; The first polysilicon layer is thermally oxidized into an oxide layer, or the first polysilicon layer is removed and then the oxide layer is thermally grown again so that the oxide layer does not fill the deep trench; the second polysilicon layer is continued to be deposited in the deep trench. And fill the deep trench, the doping type of the second polysilicon layer is the same as the polysilicon gate of the MOS device; when making the polysilicon gate of the MOS device, a polysilicon field plate is simultaneously formed in the area of ​​the terminal structure. The terminal structure and its manufacturing method of the present invention have simple implementation process and design method, are fully compatible with the process of deep groove superjunction MOS devices, have obvious voltage dividing effect and save chip area.

Description

Technical field [0001] The present invention relates to the technical field of semiconductor manufacturing. Specifically, the present invention relates to a method for manufacturing a terminal structure of a deep trench super junction MOS device. Background technique [0002] Power MOSFETs are widely used in low- and medium-range applications due to their high input impedance, low loss, fast switching speed, no secondary breakdown, wide safe working area, good dynamic performance, easy coupling with the front pole to achieve large current, and high conversion efficiency. Power conversion and control field. Although the power processing capability of power MOS devices has been amazingly improved, the conduction loss of power MOS devices increases rapidly with the increase of withstand voltage due to the on-resistance Ron in the high voltage field. In order to improve the withstand voltage and reduce the conduction loss, a series of new structures and new technologies have emerged...

AI Technical Summary

Problems solved by technology

[0005] However, the preparation of the traditional super junction structure requires multiple photolithography, ion implantation, push and epitaxial growth, the process is complex and the cost is very high

In addition, the super-junction structure with the shape of "candied haws" formed by this method has the disadvantage of uneven joint surface, which easily causes leakage when the cold MOS device is working, thereby reducing the electrical performance of the device

[0006] In order to overcome the complex manufacturing process and structural shortcomings of the traditional super-junction structure, a deep-groove super-junction structure with simple process and good controllability has recently appeared.

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