Separated gate trench MOS device and manufacturing method thereof

Abstract

The invention discloses a separated gate trench MOS device and a manufacturing method thereof, and the manufacturing method comprises the steps: carrying out the etching in a substrate to form a first depth trench, sequentially forming a first field oxide layer and a first protection layer at the bottom and on the side wall of the first depth trench, and then carrying out the etching from the bottom of the first depth trench, after the first protection layer and the first field oxide layer at the bottom of the first depth groove are etched in sequence, etching is continued to form the second depth groove and the side wall protection layer, due to protection of the side wall protection layer, the first depth groove can be further etched to form the second depth groove, and in addition, the thickness of the second depth groove is reduced. The shield gate in the second depth trench is equal to the second depth trench in height, and when the inter-electrode isolation layer is formed above the shield gate, the thickness of the inter-electrode isolation layer can be better controlled, electric leakage between the shield gate and the control gate is avoided, and the situation that the wafer stress is affected by stress caused by the thicker inter-electrode isolation layer can also be avoided; and the uniformity of the wafer is improved.

Description

technical field [0001] The invention relates to the field of semiconductor manufacturing, in particular to a split gate trench MOS device and a manufacturing method thereof. Background technique [0002] SGT (split-gate-trench, separated gate trench) structure MOS device, because of its charge coupling effect, can obtain a higher breakdown voltage under the same epitaxial specification with the same doping concentration. The structure utilizes the shielding gate electrode to shield the capacitive coupling effect between the control gate electrode and the device epitaxial layer to reduce gate-drain parasitic capacitance. The split-gate trench MOS device has lower gate charges and no degradation of on-resistance at the same time, which is beneficial to the improvement of switching characteristics and working efficiency of a power management system. The structure includes a shielding gate and a control gate, an inter-electrode oxide is required between the shielding gate and t...

AI Technical Summary

Problems solved by technology

The structure includes a shielding gate and a control gate, an inter-electrode oxide is required between the shielding gate and the control gate, and an inter-gate oxide is required on the outer layer of the control gate. In the prior art, the inter-electrode oxide and the inter-gate oxide are simultaneously However, in order to ensure that there is no leakage between the shield gate and the control gate, the thickness of the inter-gate oxide must be greater than 800 Å. In this case, the thickness of the inter-gate oxide cannot be controlled, which makes it impossible to meet the requirements of low gate open devices.

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