Semiconductor device and forming method thereof, vertical double diffused metal oxide semiconductor (VDMOS) transistor and forming method of VDMOS transistor

Abstract

The invention discloses a semiconductor device and a forming method thereof, a vertical double diffused metal oxide semiconductor (VDMOS) transistor and a forming method of the VDMOS transistor. The forming method of the semiconductor device comprises the following steps of: providing a semiconductor substrate, wherein the semiconductor substrate comprises a core device area and a marginal area, and an epitaxial layer is formed on the semiconductor substrate; forming a gate dielectric layer and a polysilicon layer on the epitaxial layer in sequence; etching the polysilicon layer and the gate dielectric layer until the epitaxial layer is exposed to form a polysilicon gate, wherein the width of the polysilicon gate adjacent to the marginal area is minimum; performing ion implantation on the semiconductor substrate by taking the polysilicon gate as a mask; and forming a well area in the epitaxial layer between the polysilicon gates, wherein a distance between the two adjacent well areas is a node distance, and the node distance closest to the marginal area is minimum. By the semiconductor device and the forming method thereof, the VDMOS transistor and the forming method of the VDMOS transistor, the breakdown voltage can be effectively prevented on the sub-marginal well area, so that the voltage endurance capability of the overall semiconductor device is improved.

Description

technical field [0001] The invention relates to the field of semiconductor manufacturing, in particular to a semiconductor device and its forming method, a VDMOS transistor and its forming method. Background technique [0002] With the continuous development of semiconductor process technology, products based on BCD (Bipolar / CMOS / DMOS) can integrate complex control functions, making it a mainstream process technology for power integrated circuits. The BCD process can select different devices for different circuits to optimize the corresponding sub-circuits, and realize the requirements of low power consumption, high integration, high speed, high driving capability, and high current of the entire circuit. [0003] High-voltage MOS transistors appearing in the existing BCD process include LDMOS (Lateral Double-diffused Metal-Oxide-Semiconductor) transistors and VDMOS (Vertical Double-Diffused Metal-Oxide-Semiconductor) transistors. where in VDMOS transistors, such as figure ...

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Problems solved by technology

[0006] The problem solved by the present invention is to provide a semiconductor device and its forming method, a VDMOS transistor and its forming method, so as to solve the problem that the breakdown voltage of the semiconductor device easily occurs on the p-well region of the secondary edge in the existing technology, and improve the reliability of the entire semiconductor device. Pressure capacity

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