Radio frequency lateral double diffused field effect transistor and its manufacturing method

Abstract

The invention discloses a radio frequency horizontal double-diffusion-field effect transistor. An epitaxial layer is developed on a P type substrate. The structure of the epitaxial layer is a stepped structure of a P type light dope epitaxial layer, an N type light dope epitaxial layer, a P type heavy dope epitaxial layer, and an N type heavy dope epitaxial layer from bottom to top. Radio frequency lateral diffusion of metal-oxide-semiconductor (RFLDMOS) of the radio frequency horizontal double-diffusion-field effect transistor is provided with RDSON which is lower than RDSON of a normal RFLDMOS and larger BV and meanwhile provided with smaller output capacitance. Meantime, the radio frequency horizontal double-diffusion-field effect transistor adopts an epitaxial growth technology, the thickness, the conduction type, the dosage concentration and the like of the epitaxial layer are easy to control, and an ion implantation and a photoetching process in a drift region is reduced once.

Description

technical field [0001] The invention relates to a semiconductor integrated circuit, in particular to a radio-frequency lateral double-diffusion field-effect transistor, and in addition, the invention also relates to a manufacturing method of the transistor. Background technique [0002] With the advent of the 3G era, more and more communication fields require the development of more powerful radio frequency (RF) devices. Radio Frequency Lateral Double Diffused Field Effect Transistor (RFLDMOS), due to its very high output power, has been widely used in portable wireless base station power amplification as early as the 1990s, and its application frequency is 900MHz-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] The current structure of RFLDMOS is as follows figure 1 As shown, a substrate doped with a high concentration of P-type...

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Problems solved by technology

[0003] The current structure of RFLDMOS is as follows figure 1 As shown, a substrate doped with a high concentration of P-type impurities is used, that is, a P-type substrate 11, and P-type epitaxial layers 12 of different thicknesses and doping concentrations are grown on the P-type substrate 11 according to the requirements of the withstand voltage of the device. , using ion implantation and diffusion process to form P-type polysilicon plug or metal plug 13, forming P well 14, oxide layer 17 and polysilicon gate 15; lightly doped drift region (LDD) 18; Faraday shielding layer 16, P+ region 19, N+ source region 110 and N+ drain region 111; this structure has a lightly doped drift region (LDD) 18 at the drain end, so that it has a larger breakdown voltage (BV), but because the concentration of the drift region 18 is relatively high Light, so that it has a large on-resistance (Rdson)

And if the on-resistance of the RFLDMOS device is large, the output power will also be reduced.

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