Silicon germanium heterojunction bipolar transistor structure

Abstract

The invention discloses a silicon germanium heterojunction bipolar transistor (SiGe HBT) structure, which is designed for overcoming a defect of high parasitic capacitance between a base electrode and a collector in a current structure. According to the provided SiGe HBT structure in the invention, there is no collector region below an external base region along a direction vertical to a substrate as well as there is no conducting layer that is connected with a collector. The processing procedure of the SiGe HBT structure is as follows: two N<+>buried layer regions that are symmetrical to each other along a center line are manufactured on a P type substrate and an N<-> silicon layer is grown; an N<+>Sinker, a P<->region and an isolating ring are formed; N type impurities are implanted into a collector region; a dielectric layer and polysilicon are deposited; a window is opened at a corresponding collector region as well as monocrystal SiGe is grown in the window and polycrystal SiGe is grown outside the window; windows are opened at an emitter and a collector and N type polysilicon is deposited; and a dielectric layer is deposited and electrodes are arranged. According to the invention, the provided SiGe HBT structure is suitable for a device having a requirement on a high radio frequency performance, especially for a device having a breakdown voltage BVceo greater than 8V.

Description

technical field [0001] The invention relates to a germanium-silicon heterojunction bipolar transistor structure. Background technique [0002] Silicon-germanium heterojunction bipolar transistors (SiGe HBTs) with band-engineering characteristics have significantly better performance than conventional silicon bipolar transistors. The energy band structure of NPN SiGe HBT is conducive to the injection of electrons in the emitter region to the base region, and at the same time inhibits the injection of holes in the base region into the emitter region, thus improving the injection efficiency of the emitter. The current gain is mainly determined by the energy band instead of Only determined by the impurity concentration ratio of the emitter region and the base region, the impurity concentration of the base region can be greatly increased, so that the base region is very thin but the base region resistance can be small, so that the device has good frequency, power gain and noise ...

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Problems solved by technology

N as collector + buried layer and N - In addition to the oxide layer above the region, there are also outer base regions and base metal connections, which inevitably form a parasitic capacitance between the base (B) and collector (C), which reduces the radio frequency (RF) of the device. )performance

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