Trench gate structure with shielding gate and manufacturing method of trench gate structure

Abstract

The invention discloses a trench gate structure with a shielding gate. The trench gate structure comprises a trench, a thermal oxidation film layer, a nitridation film layer and a deposition and oxidation film layer, wherein the trench is formed in an epitaxial layer; the thermal oxidation film layer, the nitridation film layer and the deposition and oxidation film layer are formed on the inner side surface of the trench; the trench is completely filled with a first polysilicon layer; the deposition and oxidation film layer at the top of the trench is removed; the first polysilicon layer in the removal area is completely oxidized; the nitridation film in the removal area is also removed after being oxidized; the removal area is filled with a second polysilicon layer; a polysilicon gate comprises the second polysilicon layer; a gate oxidation layer comprises the thermal oxidation film layer isolated between the polysilicon gate and the epitaxial layer; and the shielding gate comprises the residual first polysilicon layer in the bottom of the trench. The invention further discloses a manufacturing method of the trench gate structure with the shielding gate. The stray capacitance between a gate and a source can be reduced; the withstand voltage between the gate and the source can be improved; the reliability of a device is improved; and the process cost can be reduced.

Description

technical field [0001] The invention relates to the field of semiconductor integrated circuit manufacturing, in particular to a trench gate structure with a shielding gate; the invention also relates to a manufacturing method of the trench gate structure with a shielding gate. Background technique [0002] like figure 1 As shown, it is a schematic diagram of an existing trench gate structure with a shield gate (ShieldGateTrench, SGT); the trench 102 of the trench gate structure with SGT is formed on an epitaxial layer such as a silicon epitaxial layer 101, and the bottom of the trench 102 and A liner oxide layer (lineroxide) 103 is formed on the side wall surface, and the first polysilicon layer 104 completely fills the trench 102 formed with the liner oxide layer 103, and the first polysilicon layer 104 formed in the trench 102 Used to form shielding grids. The substrate oxide layer 103 at the top of the trench 102 is removed, and a gate oxide layer (gateoxide) 105 is sim...

AI Technical Summary

Problems solved by technology

[0015] The shielding gate 104 realizes isolation between the gate and the drain, that is, GD, that is, the shielding gate 104 can realize the shielding of the gate and the drain, and can effectively reduce the parasitic capacitance between the gate and the drain, that is, Cgd; but in this structure The shielding gate 104 has a large area overlapping with the polysilicon gate 107, so the parasitic capacitance between the gate and the source, that is, Cgs, will be increased at the same time, and Cgd and Cgs are in the figure 1 marked out

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