Film structure and method for isolation of SiGeHBT (silicon germanium heterojunction bipolar transistor) emitter from base

Abstract

The invention discloses a film structure and a method for isolation of a SiGeHBT (silicon germanium heterojunction bipolar transistor) emitter from a base. The SiGeHBT emitter and the base are in a composite film structure comprising silicon dioxide, polycrystalline silicon and silicon nitride from bottom to top. The novel film structure is used for isolation of the triode emitter from the base, and the over-etching quantity is reduced by decreasing the thickness of a silicon oxide dielectric layer so that increase of the lateral dimension is decreased. Simultaneously, generation and accumulation of repeatedly produced polymer are avoided by partial dry etching of the silicon dioxide, and the quantity of the silicon dioxide in dry etching is further decreased, so that increase of the lateral dimension is decreased. By the aid of the intrinsic polycrystalline silicon, thinning of the silicon oxide dielectric layer is realized, and small enough capacitance is maintained. The silicon nitride covered on the surface of the intrinsic polycrystalline silicon is capable of avoiding subsequent polycrystal of the emitter from doping and diffusing into the intrinsic polycrystal.

Description

technical field [0001] The invention relates to a semiconductor device structure and method, in particular to a silicon germanium heterojunction bipolar transistor structure and method. Background technique [0002] At present, in radio frequency applications, higher and higher device characteristic frequencies are required. Although radio frequency complementary metal oxide semiconductor (RFCMOS) can achieve higher frequencies in advanced process technologies, it is still difficult to fully meet radio frequency requirements. For example, it is difficult Achieving a characteristic frequency above 40GHz, and the R&D cost of advanced technology is also very high; compound semiconductors can realize very high characteristic frequency devices, but due to the disadvantages of high material cost and small size, and the toxicity of most compound semiconductors, it is limited. application. Silicon germanium heterojunction bipolar transistor (SiGe HBT) is a good choice for ultra-hig...

AI Technical Summary

Problems solved by technology

At the same time, because this layer of silicon dioxide has been subjected to a part of dry silicon dioxide etching first, resulting in the accumulation of heavy by-product polymers on the surface, blocking the normal etching of the chemical solution, so it is necessary to further add additional chemical solution processing events, further increasing the amount of wet overetch

This results in lateral expansion of the emitter window, degrading device performance

Images