Trench mosfet device and fabrication method thereof

Abstract

The invention provides a trench MOSFET device and a manufacturing method thereof. The manufacturing method includes: providing a substrate including an epitaxial layer; forming a trench in the epitaxial layer; forming in the trench sequentially by deposition and etching The first insulating layer, the first grid, the second insulating layer, and the second grid; forming a well area and a source area on both sides of the trench by ion implantation; forming a contact area, a trench type contact area, and a metal plug. By making the first gate and the second gate separated, the first insulating layer between the lower part of the first gate and the epitaxial layer has a larger thickness, and the thickness between the second gate and the well region and the source region is The second insulating layer has a smaller thickness, and the two separated gates are connected through metal plugs, which can make the device have a very good high-voltage resistance while obtaining a lower threshold voltage; and the device's The performance is stable, the preparation process is relatively simple, and the preparation cost is low.

Description

technical field [0001] The invention relates to the technical field of semiconductor manufacturing, in particular to a trench MOSFET device and a manufacturing method thereof. Background technique [0002] MOSFET (Metal-Oxide-Semiconductor Field Effect Transistor, Metal-Oxide-Semiconductor Field Effect Transistor) parameters such as response speed, switching current ratio, and threshold voltage all affect the performance of the final device. In order to improve the response speed of the MOSFET transistor, the switching current ratio and reduce the threshold voltage of the MOSFET transistor, the thickness of the gate oxide layer needs to be continuously reduced. However, the thinner the gate oxide layer is, the easier it is to be broken down by the charge accumulated in the gate electrode at a higher gate voltage, thus causing damage to the MOSFET transistor. [0003] In order to make the MOSFET transistor have better withstand voltage performance under the premise of high r...

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Problems solved by technology

However, this structure requires very good insulation between the gate 7 and the polysilicon protection electrode 6, which not only increases the difficulty of the process, but also is not conducive to ensuring the high-voltage resistance of the device, resulting in poor stability of the device, and The device process steps for manufacturing this structure are complicated and the manufacturing cost is high

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