Trench metal-oxide-semiconductor field effect transistor (MOSFET) with shallow trench structure and manufacturing method thereof

Abstract

The invention discloses a trench metal-oxide-semiconductor field effect transistor (MOSFET) with a shallow trench structure and a manufacturing method thereof. Compared with the trench MOSFET in the prior art, the trench MOSFET with a shallow trench structure in the invention has smaller grid charge and lower source and drain resistance, and meanwhile, maintains the breakdown voltage required by the device. In some preferable embodiments, the upper surface of the conducting region in the trench grid, which is connected with the grid metal, is higher than the upper surface of the conducting region in the trench grid of the active region, thereby further avoiding the possible phenomenon of excessive etching in the etching process of the grid contact trench.

Description

technical field [0001] The invention relates to a unit structure, a device structure and a manufacturing process of a semiconductor power device. In particular, it relates to a novel cell and terminal structure of a trench MOSFET (Metal Oxide Semiconductor Field Effect Transistor) with a shallow trench structure, which has low source-drain resistance (Rds), low gate charge (Qg) and higher breakdown voltage (BV). In addition, the present invention particularly relates to an improved process for manufacturing such trench MOSFETs. Background technique [0002] In order to solve the problem that traditional trench MOSFETs usually have relatively high Qg, a trench MOSFET with a shallow trench structure is disclosed in the prior art, as shown in Figure 1, that is, the trench gate in the epitaxial layer The depth Td (such as figure 2 shown) is shallower than conventional trench MOSFETs, so the meaning of the term "shallow trench" will be clear to those of ordinary skill in the a...

AI Technical Summary

Problems solved by technology

This shallow trench structure in the prior art does reduce the Qg of the trench MOSFET, however, this method of reducing Qg only by reducing the trench depth Td will lead to an increase in the device Rds (such as image 3 shown in the upper curve)

On the other hand, if the trench depth is too shallow, the gate contact trench etched in the trench fill is likely to be over-etched during the contact trench etching process, allowing the contact trench to extend into the epitaxial layer. , so that a short circuit occurs between the metal plug filled in the gate contact trench and the epitaxial layer

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