Method for making side wall between base and emitter of high frequency triode

Abstract

The invention provides a method for making a side wall between a base and an emitter of a high frequency triode. The method comprises a step of providing a substrate, forming an N epitaxial layer, a first polysilicon layer and a first TEOS layer on the surface of the substrate, a step of forming a base region trench which goes through the first polysilicon layer and the first TEOS layer, a step of forming a P type diffusion area at the N epitaxial layer under a first P polysilicon layer, and carrying out base region doping on the N epitaxial layer to form a base region, a step of orderly forming a second polysilicon layer and a second TEOS layer on the base region, in the base region trench and on the first polysilicon layer and the first TEOS layer, a step of etching the second polysilicon layer by using a dry method to form a polysilicon side wall, and a step of using a wet method to corrode the second TEOS layer to remove the second TEOS layer on the first TEOS layer and at the middle part of the base region, and retaining the second TEOS layer which is in contact with the polysilicon side wall, wherein the retained second TEOS layer is taken as the side wall between the base and the emitter.

Description

【Technical field】 [0001] The invention relates to the technical field of semiconductor devices, in particular to a method for manufacturing a sidewall between a base and an emitter of a high-frequency triode. 【Background technique】 [0002] High-frequency triodes are distinguished from ordinary triodes by their small transistor feature size, low breakdown voltage, high characteristic frequency, and difficult manufacturing process. It is generally used in high-frequency broadband low-noise amplifiers such as VHF, UHF, CATV, wireless remote control, and radio frequency modules. These applications are mostly used in low-voltage, small-signal, low-current, and low-noise conditions. [0003] In order to achieve the highest characteristic frequency, the parasitic capacitance of the device must be reduced as much as possible, and the junction depth of the emitter region and the base region should be made as shallow as possible. Traditional high-frequency triodes usually use polycr...

AI Technical Summary

Problems solved by technology

In particular, making L-shaped sidewalls in the existing process may cause the LPTEOS layer to be corroded, and then the thickness of the LPTEOS layer on the top of the polysilicon will be greatly reduced, and the L-shaped sidewalls left after etching will symmetrically protrude from the TEOS layer. The flatness of the surface of the device is deteriorated, which also has an adverse effect on the subsequent metal interconnection

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