Modélisation électrothermique et analyse de l'auto- échauffement d'un TBH SiGe réalisé en technologie BiCMOS0.13µm pour la conception de circuits RF.

Abstract

The aim of this thesis, being the electrothermal modeling and analysis of the self-heating ""Self Heating"" of a HBT SiGe realized in BiCMOS9MW0.13µm technology. The architecture used for the design of the BiCMOS9MW bipolar transistor is a self-aligned structure by base epitaxy. In the literature, it is referred to by the English acronym DPSA-SEG (Double Polysilicon, Self Aligned by Selective Epitaxial). An analysis of the effect of self-heating on HBT SiGe from a BiCMOS9 0.13µm die ; was made, using the COMSOL software, in order to better understand the distribution of heat on the surface of the component, and to approach the hottest point of the HBT SiGe. We also simulated the static and dynamic electrical parameters of the component : the static gain (β), the transition frequency and the maximum oscillation frequency (fT, fmax), the maximum temperature (Tmax) reached by the HBT and its resistance thermal RTH. The analysis of the self-heating can be improved by variants during the realization of the transistor. In this context, it would be preferable to reduce the creation of heat and to minimize the effects of “Self Heating”. We have analyzed the influence of the percentage of germanium on the self-heating of the transistor ; we analyzed the distribution of heat on the surface of the component for the three percentages of germanium x= (10%, 20%, 30%) the higher the rate of germanium increases the heat spreads over the entire surface of the HBT. However, we were interested in studying the influence of the position of the extrinsic base (EB) in polysilicon compared to the intrinsic SiGe base in order to see the impact of self-heating and the static electrical performance and dynamics of TBH SiGe from a BiCMOS9MW 0.13µm die. We noted that the maximum current gain and cut-off frequencies for polysilicon above the base increases compared to a structure with polysilicon below. Nevertheless, the self-heating of the device is greater. In the case where the Polysilicon is located on the surface of the device in comparison with the second case where it is reduced by 92 K. It is therefore preferable to have a structure with poly base at the bottom of the SiGe base in order to reduce the self-heating of the component. In addition, we were interested in the reduction of self-heating in a SiGe HBT (SiliciumGermanium-based Heterojunction Bipolar Transistor) using the Peltier effect. The electrothermal model integrates in the structure, a cooling by using the elements with ""Peltier effect"". We have analyzed the distribution of heat over the entire HBT component, which heats up in the case of selfheating up to a maximum temperature of (Tmax = 467K). By integrating the Peltier effect cooling in the HBT SiGe, there is a significant drop in temperatures at (Tmax = 330K)