Manufacturing method and structure of asymmetric high-voltage MOS device

Abstract

The invention discloses a manufacturing method of an asymmetrical high-voltage MOS (metal oxide semiconductor) device. The method comprises the following steps of: adjusting the sizes of the shallow trench isolation areas of the source region and the source end in a layout design process; keeping the total transverse sizes of the shallow trench isolation areas of the source region and the source end unchanged; reducing the transverse size of the shallow trench isolation area of the source end; increasing the transverse size of the source region; and in a manufacturing process, forming a shallow trench at the source end of the device by use of the layout of the shallow trench isolation area of the source end after the size adjustment. The invention also discloses a structure of an asymmetrical high-voltage MOS device. Through the invention, the equivalent via resistance at the source end is reduced and the drive current of the device is increased under the condition of keeping the total size of the device unchanged.

Description

technical field [0001] The invention relates to the field of manufacturing semiconductor integrated circuits, in particular to a method for manufacturing an asymmetric high-voltage MOS device, and the invention also relates to the structure of an asymmetric high-voltage MOS device manufactured by the method. Background technique [0002] In the structure of the existing asymmetric high-voltage MOS device, the source region and the body region of the corresponding source end are often adjacent to and connected together in order to save area. Existing asymmetric high-voltage NMOS devices are formed in a high-voltage P well on a silicon substrate, and an N-type drift region at the active end, an N-type drift region at the drain end, a P well at the source end, and a P well at the drain end are formed in the high-voltage P well. well; the P well at the source end, the P well at the drain end and the high voltage P well form a body region; the P well at the source end is in conta...

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Problems solved by technology

However, a problem caused by the high doping concentration of the P well in the body region is that, since the P well is connected to the source region on the side of the source region, the lateral diffusion of the P well will make the source end That is, the cross-section of the current path on the source region side becomes narrower, that is, the equivalent path resistance at the source end becomes larger, so that the driving current of the device is relatively small

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