ldmos device and its manufacturing method

Abstract

The invention discloses an LDMOS (laterally diffused metal oxide semiconductor) device and a manufacturing method thereof. A drift region of the LDMOS device comprises a first drift region and a second drift region; the first drift region is formed by an ion implantation region formed in a selected area of a silicon substrate; the second drift region is formed by doped polysilicon formed on the surface of the silicon substrate; the second drift region is overlapped on the first drift region, and a drain region is formed in the second drift region. Owing to arrangement of the second drift region, thickness of the whole drift region is increased, and accordingly parasitic resistance of the whole drift region is reduced while effectiveness in increase of linear current of the device and reduction of on resistance of the device can be achieved. In addition, the LDMOS device is capable of keeping high breakdown voltage and is low in process cost.

Description

technical field [0001] The invention relates to the field of semiconductor integrated circuit manufacturing, in particular to a lateral field effect transistor (LDMOS device; the invention also relates to a method for manufacturing the LDMOS device. Background technique [0002] Lateral Field Effect Transistor (LDMOS) is a commonly used semiconductor high-voltage device, which is widely used in power management, LCD and LED driving, ESD protection and other fields. There are usually two application methods: analog application and switch application. When LDMOS is used as a switch, the device needs to have a very low on-resistance (source-drain resistance of the device in the linear region) to reduce switching power consumption. In LDMOS, the channel length is much smaller than the length of the drift region, and the on-resistance of the device is dominated by the resistance of the drift region. Therefore, in switching LDMOS, it is necessary to increase the doping concentrat...

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Problems solved by technology

However, LDMOS must meet the requirements of the breakdown voltage, and the increase of the doping concentration and the reduction of the length of the drift region are subject to certain restrictions.

The increase in the thickness of the drift region can only be formed by high-energy ion implantation and long-time well pushing in the non-epitaxial process, but this will cause excessive lateral diffusion and cause excessive short-channel effects

Epitaxial LDMOS can form a thick drift region, but the process cost increases

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