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Technologie et Physique de Transistors Bipolaires à Hétérojonction Si/SiGeC Auto-alignés très Hautes Fréquences

Abstract : The purpose of this thesis is the study and optimisation of high performance Si/SiGeC heterojunction bipolar transistors for telecommunication and radar detection applications (> 50 GHz). The first chapter is a reminder of the bipolar transistor theory, both in its static and dynamic operations. We present in the second chapter a history of the SiGe HBTs manufacturing technologies, explaining the choices leading to a fully self-aligned structure with selective epitaxial growth of the base. Results obtained in this thesis are compared with the state-of-the-art performances published in literature. Next, we study the classical optimisation of the HBT and we demonstrate how, by several optimisations made on the vertical profile and the lateral dimensions of the device, we were able to push up the fT and fMAX frequencies from 200 GHz at the beginning of the thesis up to 300 GHz. The possibility to increase the collector to emitter breakdown voltage BVCEO is demonstrated using innovative process features, such as metallic emitter, Ge insertion in the emitter, and neutral base recombination. Significant improvements of BVCEO are demonstrated, which enables state-of-the-art fT × BVCEO products (> 400 GHz.V). The study of the temperature behaviour of the HBT is presented in the last part of the thesis: First, we describe the self-heating of the transistor, and its impact on dynamic performances. Technological variations enable the reduction the self-heating, such as DTI depth diminution and emitter fragmentation, and a simple model for RTh calculation is developed. We finish off with the study of the HBT at cryogenic temperatures. Since fT and fMAX are strongly improved at low temperature (more than 400 GHz), we can deduct from the extraction of the different transit times interesting perspectives for further optimization of the device, with the goal to reach transition frequencies around 1 THz.
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Contributor : Benoit Barbalat <>
Submitted on : Thursday, December 20, 2007 - 9:25:57 AM
Last modification on : Wednesday, September 16, 2020 - 4:57:21 PM
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  • HAL Id : tel-00139028, version 1



Benoit Barbalat. Technologie et Physique de Transistors Bipolaires à Hétérojonction Si/SiGeC Auto-alignés très Hautes Fréquences. Micro et nanotechnologies/Microélectronique. Université Paris Sud - Paris XI, 2006. Français. ⟨tel-00139028⟩



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