Shield grid trench MOSFET device and manufacturing method thereof

Abstract

The invention discloses a shield grid trench MOSFET device.In grid electrode structures of primitive cells, shield electrodes are formed after epitaxial layers filling trenches are etched back, and trench grids are formed at the tops of the shield electrodes; the shield electrodes and adjacent drift regions make direct contact, carrier balance is achieved, the shield electrodes of the primitive cells and the drift regions form alternately-arranged structures in the transverse direction, and the shield electrodes carry out transverse exhausting on the adjacent drift regions in reverse bias of the device.The invention further discloses a manufacturing method of the shield grid trench MOSFET device.According to the shield grid trench MOSFET device and the manufacturing method, it is unnecessary to arrange dielectric films at the bottoms of the shield electrodes, stepping of device units can be reduced, the specific on-resistance of the device can be reduced, manufacturing difficulty can be lowered, and the uniformity of device performance can be improved.

Description

technical field [0001] The invention relates to the field of manufacturing semiconductor integrated circuits, in particular to a shielded gate trench MOSFET device; the invention also relates to a manufacturing method of the shielded gate trench MOSFET device. Background technique [0002] Such as figure 1 As shown, it is a schematic structural diagram of an existing shielded gate trench MOSFET device; the current flow region of the existing shielded gate trench MOSFET device is composed of a plurality of primitive cells arranged periodically, each of which includes: [0003] An N-type epitaxial layer 102 formed on the surface of a semiconductor substrate such as a silicon substrate 101, a trench 511 is formed in the N-type epitaxial layer 102, the shielding electrode 411 is composed of polysilicon filled at the bottom of the trench 511, and the trench gate 421 It is composed of polysilicon filled on the top of the trench 511; a shielding dielectric film 311 is isolated bet...

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Problems solved by technology

[0010] figure 1 In the shielded gate structure of the existing structure shown, the shielding dielectric film needs to reach a certain thickness to withstand the source-drain voltage. Generally, for a 100V device, the thickness on the sidewall needs to be 5000-6000 angstroms, so that the device unit cannot Effectively shrink, cannot use higher drift region impurity concentration to reduce on-resistance

At the same time, for such a device structure, after the bottom shielding dielectric film and the shielding electrode are completed, the device gate oxide film is grown. The manufacturing process is complicated. The influence of multiple factors such as film etching leads to poor device consistency

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