RF LDMOS device

Abstract

The present invention provides an RF LDMOS device including: a P+ substrate, a P type epitaxial layer, a substrate metal, a P+ sinker region inside the P type epitaxial layer, a P trap, a N- drift region, a N+ region, polycrystalline silicon, and a Faraday cage arranged above the N- drift region and above the right side of the polycrystalline silicon. One layer of low k dielectric material is arranged between the Faraday cage and the drift region, a dielectric constant of the low k dielectric material is less than a dielectric constant of SiO2. An insulation dielectric layer arranged over the drift region and below the Faraday cage is made of low k dielectric material, and the structure can efficiently reduce a high electric field of the Faraday cage near to a drain terminal edge. Compared to a traditional structure, the device can efficiently optimize the electric field distribution on the surface of the drift region so as to uniformize the electric field distribution and improve a breakdown voltage of the device; and the device also can reduce a source-drain on resistance of the device and improve an output power of the device.

Description

Technical field [0001] This application relates to the field of semiconductor devices, specifically a LDMOS field effect transistor for radio frequency applications. Background technique [0002] Radio frequency LDMOS (Laterally Double-Diffused Metal Oxide Semiconductors) field effect transistor is a high-power radio frequency device with a wide range of applications. It has the advantages of good linearity, high power gain, high voltage resistance, good matching performance, high output power and low cost. It is widely used Used in the fields of wireless communications, mobile base stations, radar and navigation. [0003] In the application of high-power radio frequency LDMOS devices, it is generally desired that the devices have a large breakdown voltage, a large output power and a high frequency characteristic. In the RF LDMOS design process, in order to improve the performance of the device, the general goals pursued are: large breakdown voltage, low on-resistance, large satur...

AI Technical Summary

Problems solved by technology

However, in conventional RF LDMOS, there is an electric field peak at the right edge of the Faraday cage, which makes the device prone to breakdown

In addition, a larger electric field in the drift region will increase the surface scattering in the drift region and reduce the carrier mobility, thereby reducing the saturation current of the device

The breakdown voltage of RF LDMOS has a trade-off relationship with the cut-off frequency, and the traditional Faraday shield reduces the parasitic capacitance C gd , and also introduces a high electric field near the edge of the Faraday cage near the drain, which affects the robustness of the device

Images