Method for manufacturing groove type MOS transistor

Abstract

The invention discloses a manufacturing method of trench-MOS transistor, aiming at lowering the capacitor between the gate and drain, and increase switching rate of transistor. This method includes the following steps: use dry etching to form a deep trench; grow a layer of sacrificial oxide film; then continue to use the technique of high-density plasma deposition to grow a layer of high-density growth of the plasma membrane in the bottom and the wall of mentioned trench; and then use certain liquid to remove the oxide film on the surface of mentioned trench. That removal of oxide film contains sacrificial oxide film and high-density Plasma oxide film; then continues to grow a layer of the gate oxide film in the bottom and on the wall of the mentioned trench wall; then perform the growth and carve of polysilicon within the trench.

Description

technical field [0001] The invention relates to a manufacturing method of a semiconductor device, in particular to a manufacturing method of a trench type MOS transistor capable of reducing bottom capacitance. Background technique [0002] In power devices, switching characteristics have gradually become a main parameter to measure the performance of these devices, and to improve their switching characteristics must reduce their overall capacitance. At present, the manufacturing method of trench MOS transistors is generally as follows: (1) forming a deep trench by dry etching; (2) growing a sacrificial oxide film through a diffusion furnace; (3) removing the sacrificial oxide film; (4) Growth of gate oxide film; (5) growth of gate polysilicon; (6) etching back gate polysilicon below the silicon plane; (7) lithography implantation of base region and source region; (8) growth of interlayer film and contact hole formation; (9) front metal sputtering and etching; (10) back thin...

AI Technical Summary

Problems solved by technology

[0003] As shown in Figures 1 and 2, the trench MOS transistor manufactured by the above method has a gate oxide film that is thinner at the bottom of the trench than at the sidewalls, resulting in a large gap between the gate and the drain. large capacitor

However, if the capacitance is reduced by increasing the thickness of the oxide film, it is easy to cause the oxide film on the side wall to become thicker at the same time, which will lead to an increase in the turn-on voltage and on-resistance, thereby increasing the overall power consumption of the transistor.

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