SGTMOSFET device and manufacturing method

Abstract

Dsiclosed is an SGTMOSFET device and a manufacturing method. A bottom oxide layer and source polycrystalline silicon of a grid structure are located at the bottom of a grid groove, the thickness of the bottom oxide layer meets the requirement for voltage resistance of 150V or above, the top of the grid groove is filled with a top oxide layer completely formed through CVD deposition, a polycrystalline silicon grid is formed in a top sub-groove formed by etching the top oxide layer, the width of the top sub-groove meets the requirement for filling the polycrystalline silicon grid, and when the depths of the two side faces of the top sub-groove are the same, the depths of the two side faces of the polycrystalline silicon grid are the same. The invention further provides a manufacturing method of an SGTMOSFET device. According to the invention, under the condition of ensuring that the bottom oxide layer realizes the withstand voltage of more than 150V, the polycrystalline silicon grid with a left-right structure is adopted, so that the width of the polycrystalline silicon grid can realize good and low-difficulty filling of the polycrystalline silicon grid, and the depths of the two side surfaces of the polycrystalline silicon grid can be ensured to be consistent; therefore, the increase of input capacitance can be avoided and the reliability of the device can be improved under the condition of meeting the coverage length of a channel region.

Description

technical field [0001] The invention relates to a method for manufacturing a semiconductor integrated circuit, in particular to a method for manufacturing a Shield Gate Trench (ShieldGate Trench, SGT) MOSFET device. Background technique [0002] Compared with IGBT, MOSFET is a multi-sub device, because there is no minority sub-injection and recombination during the switching process, so its switching speed is fast and it has been widely used. Compared with the traditional planar MOSFET, the trench MOSFET greatly reduces the channel resistance, but the on-resistance of the drift region is proportional to the 2.5th power of the breakdown voltage, which makes the resistance of the drift region become unacceptable. [0003] In order to reduce the on-resistance in the drift region, SGTMOSFET was proposed. SGTMOSFET inserts a vertical field plate in the drift region, and this field plate is connected to the source voltage. In the process of bearing the breakdown voltage, the dr...

AI Technical Summary

Problems solved by technology

This increases the device's input capacitance (Ciss), which is the parallel capacitance of the gate-to-source capacitance (Cgs) and the gate-to-drain capacitance (Ggd)

And the appearance has become ugly

The shape of the polysilicon gate 6a may form some sharp corners, which will cause the device to form a spike in the electric field, which will also have some impact on the reliability of the device

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