Low-voltage shield gate MOSFET device and manufacturing method thereof

Abstract

The invention discloses a low-voltage shield gate MOSFET device and a manufacturing method thereof. The low-voltage shield gate MOSFET device comprises an MOSFET device body, wherein the MOSFET device body mainly comprises an N epitaxial silicon substrate and a plurality of grooves etched in the N epitaxial silicon substrate, a field oxide layer is formed on the inner wall of the middle lower part of each groove, the field oxide layer is filled with a layer of shield gate polycrystalline silicon, the top part of the shield gate polysilicon is provided with an inter-gate oxide layer, the top part of the inter-gate oxide layer is provided with a control gate and a gate oxide layer, and the gate oxide layer is formed on the upper side walls of the grooves; and a layer of drain electrode formed by metal is arranged on the back surface of the N epitaxial silicon substrate. The manufacturing method mainly comprises the steps of: after the shield gate is formed, an oxide layer is grown on the side wall of the groove and the top part of the shield gate through using a thermal oxidation technology, the oxide layer is thick enough and can completely fill the grooves in the upper portion of the shield gate, and then the oxide layer is etched back to form the inter-gate oxide layer between the shield gate and the control gate.

Description

technical field [0001] The invention relates to the technical field of power semiconductor devices, in particular to a low-voltage shielded gate MOSFET device and a manufacturing method thereof. Background technique [0002] Compared with the traditional trench MOSFET, the shielded gate MOSFET device has the advantages of low on-resistance and low switching loss, so its application in the medium and low voltage power semiconductor market is gradually increasing. The gate of the shielded gate trench MOSFET structure includes both the shielded gate and the control gate. The existence of the shielded gate makes the longitudinal electric field similar to the rectangular distribution when the device breaks down. Compared with the traditional trench MOSFET, the epitaxy with a smaller resistivity is easier A higher breakdown voltage can be obtained, so that the device has a smaller on-resistance. According to the relative positions of the shielded gate and the control gate in the ...

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Problems solved by technology

The cost of this process method is relatively high; and as the device size decreases, the trench width decreases, and the aspect ratio of HDP filling exceeds the optimal range, resulting in uneven filling thickness of the oxide layer between the gates of the device, and Problems such as voids are prone to occur, resulting in large device leakage and poor reliability

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