Shielding gate MOS structure with gradually changing oxide layer

Abstract

The invention provides a shielding gate MOS structure with a gradually changing oxide layer. The characteristics lie in that the shielding gate MOS structure is divided into two parts at a trench of afirst conductive type epitaxial layer, the upper part comprises a gate conductive polycrystalline silicon and a gate oxide layer located at two sides of the gate conductive polycrystalline silicon, and the lower part comprises a gradually changing oxide layer and a shielding gate coated by the gradually changing oxide layer. According to the shielding gate MOS structure provided by the invention,the oxide layer at two sides of the shielding gate adopts a gradually changing oxide layer in structure, thereby being capable of improving the device withstand voltage, reducing the on-resistance. Meanwhile, the parasitic capacitance of the device can be reduced, and the switching characteristics of the device are optimized. The shielding gate MOS structure can reduce the chip area and save thecost at the same time.

Description

Technical field [0001] The invention relates to a MOSFET device structure, in particular a shielded gate MOS structure with a graded oxide layer, belonging to the MOSFET technical field. Background technique [0002] Metal-Oxide-Semiconductor Field-Effect Transistor (MOSFET) is a field-effect transistor that can be widely used in analog circuits and digital circuits. [0003] Such as figure 1 As shown, it is a traditional Trench MOSFET device structure, such as figure 2 Shown as the traditional shielded gate MOS structure, the withstand voltage of the two structures is the key parameter to characterize the performance of the device, and has always been the focus of attention, and the traditional shielded gate MOS structure has thick oxide on both sides of the shielding gate Layer 15, and the thickness of the oxide layer in the thick oxide layer is the same up and down, so that there are two electric field peaks in the drift region, one is at the junction of the P-type body region ...

AI Technical Summary

Problems solved by technology

[0004] The purpose of the present invention is to propose a shielded gate MOSFET device structure and its manufacturing method with excellent performance on the basis of overcoming the shortcomings of the existing shielded gate MOSFET devices. layer, which can not only improve the withstand voltage capability of the device, but also reduce the on-resistance of the device, reduce the parasitic capacitance of the device, and optimize the switching characteristics of the device

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