Trench MOSFET (Metal-Oxide-Semiconductor Field-Effect Transistor) side wall structure and manufacturing method thereof

Abstract

The invention provides a trench MOSFET (Metal-Oxide-Semiconductor Field-Effect Transistor) and a manufacturing method thereof. The manufacturing method of the trench MOSFET comprises the following steps of: (1) preparing a heavily doped substrate; (2) forming a lightly doped epitaxial layer on the heavily doped substrate; (3) forming a lightly doped trap region on the lightly doped epitaxial layer; (4) forming a plurality of grid trenches penetrating through the lightly doped trap region and being in contact with the lightly doped epitaxial layer; (5) forming a heavily doped source region at the upper part of the lightly doped trap region and among the grid trenches; (6) forming a side wall on both sides of each grid trench; and (7) forming source electrode contact holes by self alignment of the side walls, wherein the top opening of each contact hole is greater than the bottom opening. The invention can further improve the density of unit cells of MOSFET, provides convenience for etching source electrode contact holes, and is favorable for metal filling of the source electrode contact holes.

Description

technical field [0001] The invention relates to the field of power semiconductor devices, in particular to a trench type MOSFET sidewall structure of a high-density unit cell and a process and a manufacturing method thereof. Background technique [0002] MOSFET (Power Metal Oxide Semiconductor Field-effect Transistor, field effect transistor) is widely used in 4C due to its advantages of fast switching speed, good frequency performance, high input impedance, low driving power, good temperature characteristics, and no secondary breakdown problem. (ie Communication, Computer, Consumer, Car: communication, computer, consumer electronics, automobile) and other fields. [0003] The finished trench power MOSFET device is composed of a large number of MOSFET units inside. The MOSFET of each unit is called a unit cell, and the pitch between the unit cells (patch) will directly affect the importance of the power MOSFET. Electrical parameters Drain-source on-state resistance Rdson. ...

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Problems solved by technology

[0010] The purpose of the present invention is to provide a sidewall structure of a trench MOSFET to solve the problem that the existing trench MOSFET unit cell spacing is limited by the photolithographic resolution and cannot be further reduced

[0011] Another object of the present invention is to provide a trench MOSFET sidewall structure manufacturing method to solve the problem that the existing trench MOSFET unit cell spacing is limited by the photolithographic resolution and cannot be further reduced

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