Self-aligning silicide method for RF lateral diffusion field-effect transistor

Abstract

A method for radio frequency lateral diffusing self-alignment silicides of the field-effect-transistor, comprising the steps of: on the silicon chips, injecting the etched multiple crystal grids to the drifting zone without mask; depositing a thin silicon dioxide layer with tetraethylorthosilicate heat decomposition method; protecting drifting zone with photo resist and resisting silicon dioxide, forming a silicon dioxide sidewall on the gate side nearby the source; source-drain self-aligning injection and striping; quick heat annealing to eliminate injection damage and activate impurity; separately depositing a thin pad silicon dioxide with tetraethylorthosilicate heat decomposition method and depositing a silicon nitride with low pressure chemical vapour deposition method; sequentially resisting silicon nitride and silicon dioxide, forming a silicon nitride secondary sidewall on the silicon dioxide primary sidewall; sputtering a thin titanium layer; quick heat annealing to form the titanium silicides from the silicon and titanium; etching and removing the rest titanium; quick heat annealing to forming low resistance titanium silicides from high resistance ones.

Description

technical field [0001] The invention belongs to the technical field of semiconductors, in particular to a novel self-aligned silicide method for a radio frequency lateral diffusion field effect transistor (LDMOS). Background technique [0002] LDMOS has excellent radio frequency performance (large linear dynamic range, high linear gain, large output power, high power density, etc.), compared with gallium arsenide technology, which is the mainstream radio frequency process, it has low cost, simple process, mature and compatible with complementary metal - Advantages of the oxide-semiconductor (CMOS) process. At present, it is widely used in radio frequency power amplifiers (below 2GHz), and has become the mainstream of power devices in mobile communication base station power amplifiers, and plays an increasingly important role in terminal power amplifiers. [0003] However, due to the existence of the lightly doped drift region, it is difficult to realize self-aligned silicid...

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Problems solved by technology

[0003] However, due to the existence of lightly doped drift regions, conventional LDMOS is difficult to realize self-aligned silicide, and there is a large series resistance in the source and drain regions, which limits the further improvement of radio frequency performance.

In order to realize self-aligned silicide, Satoshi Matsumoto et al. proposed a method of using a single-layer silicon dioxide sidewall to define the length of the drift region and realize self-aligned titanium silicide (see IEEETRANSACTIONS ON ELECTRON DEVICES, VOL.48, NO.12, DECEMBER 2001, 2911~2916), successfully realized self-aligned silicide, but the length of the drift region fabricated by this method is limited by the width of the sidewall, which lacks design flexibility, and it is difficult to manufacture a drift region with a length greater than 0.3 microns, which cannot meet Higher withstand voltage requirements for devices

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