Radio-frequency LDMOS (Laterally Diffused Metal Oxide Semiconductor) device and manufacturing method thereof

Abstract

The invention discloses a radio-frequency LDMOS (Laterally Diffused Metal Oxide Semiconductor) device. A drift region is in a nonuniform structure formed by a first ion injection region and a second ion injection region; the first ion injection region is self-aligned to a polysilicon gate; the second ion injection region is defined by photoetching and is at a distance from the polysilicon gate; a crossover region of the first ion injection region and the second ion injection region has higher doping concentration which can improve driving current of the device and reduce switch-on resistance of the device; the lower doping concentration of the first ion injection region can reduce the intensity of an electric field on the edge of the polysilicon gate, improve breakdown voltage of the device, reduce injection capacity of a hot carrier on the edge of the polysilicon gate and improve robustness of the device; and the lower doping concentration and great depth of the second ion injection region can reduce output capacitance of the device. The invention further discloses a manufacturing method of the radio-frequency LDMOS device.

Description

technical field [0001] The invention relates to the field of semiconductor integrated circuit manufacturing, in particular to a radio frequency (RF) lateral field effect transistor (LDMOS) device; the invention also relates to a method for manufacturing the radio frequency LDMOS device. Background technique [0002] With the advent of the 3G era, more and more communication fields require the development of higher power RF devices. Due to its very high output power, the RF lateral double-diffused field effect transistor has been widely used in the power amplification of portable wireless base stations as early as the 1990s, and its application frequency is 900MHz to 3.8GHz. Compared with traditional silicon-based bipolar transistors, RFLDMOS has better linearity, higher power and gain. Today, RFLDMOS is more popular than bipolar, and GaAs devices. [0003] Such as figure 1 As shown, it is a schematic structural diagram of an existing radio frequency LDMOS device. Taking a...

AI Technical Summary

Problems solved by technology

To keep RDSON low, it is necessary to increase the doping concentration of the drift region 4 as much as possible, but this may cause the drift region 4 to not be fully depleted when a high voltage is applied to the drain region 7b, resulting in a drop in breakdown voltage

In addition, the main factor restricting the decline of Coss is the junction capacitance from the drift region 4 to the silicon substrate 1. If the concentration of the drift region 4 increases, the junction capacitance will also increase, which is also not conducive to the decline of Coss.

Therefore, the two parameters of RDSON and Coss are mutually restricted, and the existing device structure cannot reduce both of them at the same time by increasing the concentration of the drift region, so the device characteristics of the existing RF LDMOS are difficult to achieve excellent performance

Images