7-Mask Self-Aligned SiGe Base Bipolar Transistors with fT of 80 GHz

Tsutomu TASHIRO  Takasuke HASHIMOTO  Fumihiko SATO  Yoshihiro HAYASHI  Toru TATSUMI  

IEICE TRANSACTIONS on Electronics   Vol.E80-C   No.5   pp.707-713
Publication Date: 1997/05/25
Online ISSN: 
Print ISSN: 0916-8516
Type of Manuscript: PAPER
Category: Integrated Electronics
bipolar transistor,  silicon-germanium base,  selective epitaxial growth,  CMP,  trench isolation,  fT,  

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A 7-mask self-aligned SiGe base bipolar transistor has been newly developed. This transistor offers several advancements to a super self-aligned selectively grown SiGe base (SSSB) transistor which has a selectively grown SiGe-base layer formed by a cold-wall ultra high vacuum (UHV)/CVD system. The advancements are as follows: (1) a BPSG-filled arbitrarywidth trench isolation on a SOI is formed by a high-uniformity CMP with a hydro-chuck for reducing the number of isolation fabrication steps, (2) polysilicon-plug emitter and collector electrodes are made simultaneously using an in-situ phosphorusdoped polysilicon film to decrease the distance between emitter and collector electrodes and also to reduce the fabrication steps of the elecrodes, (3) a n+-buried collector layer is made by a high-energy phosphorus ion-implantation technique to eliminate collector epitaxial growth, and (4) a germanium profile in the neutral base region is optimized to increase the fT value without increasing leakage current at the base-cellector junction. In the developed transistor, a high performance of 80-GHz fT and mask-steps reduction are simultaneously achieved.