Radio frequency LDMOS (laterally diffused metal oxide semiconductor) device and manufacture method thereof

Abstract

The invention discloses a radio frequency LDMOS (laterally diffused metal oxide semiconductor) device. The side surface of a channel doping region and the side surface of a drift region of the radio frequency LDMOS device are contacted; a gate oxide and a grid electrode are successively arranged above the channel doping region and the drift region; and the doping density of the part of the drift region, which is below the channel doping region, is smaller than the doping density of rest parts. The invention also discloses a manufacture method for the radio frequency LDMOS device. Because the doping density of the drift region is unevenly distributed, the hot carrier effect can be lowered while the low-conduction resistance is obtained.

Description

technical field [0001] The present application relates to a semiconductor device, in particular to an LDMOS device applied in the radio frequency field. Background technique [0002] RF LDMOS (Laterally Diffused MOS Transistor) devices are commonly used in RF base stations and broadcasting stations. The performance indicators pursued include high breakdown voltage, low on-resistance and low parasitic capacitance. [0003] see Figure 1i , which is an existing RF LDMOS device. Taking an n-type radio frequency LDMOS device as an example, there is a p-type lightly doped epitaxial layer 2 on a p-type heavily doped substrate 1 . The epitaxial layer 2 has an n-type heavily doped source region 8 , a p-type channel doped region 7 and an n-type drift region 3 which are side-contacted in sequence. The doping concentration of the drift region 3 is uniform. In the drift region 3 there is an n-type heavily doped drain region 7 . A gate oxide layer 4 and a polysilicon gate 5 are arran...

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Problems solved by technology

The main reason is that when a high voltage is applied to the drain terminal 9, the lateral electric field of the drift region 3 is stronger; the doping concentration of the drift region 3 under the polysilicon gate 5 is higher, so the lateral electric field is stronger, thereby causing severe heat-carrying current sub-injection effect

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