| PhD Viva

Name of the Speaker: Mr. Aakashdeep Gupta (EE15D209)
Guide: Prof. Anjan Chakravorty
Online meeting link: meet.google.com/hen-adtn-bki
Date/Time: 26th June 2024 (Wednesday), 11:00 AM
Title: Thermal Modeling Of Multi-Finger Silicon-Germanium Heterojunction Bipolar Transistors

Abstract :

Critical advantages offered by Silicon-Germanium Heterojunction Bipolar Transistors (SiGe HBTs) include operation up to several GHz frequencies, attractive figure-of-merits, and integration with the existing CMOS technology nodes, and these put forward SiGe HBTs as a versatile and competitive bipolar technology. Multi-finger SiGe HBTs are usually preferred for power amplifier circuits operating at high frequency and low and medium power. However, they suffer from pronounced electro-thermal heating resulting from aggressive down-scaling, shallow and deep trenches, and high current operations. Under an actual operating condition, all the fingers dissipate heat simultaneously, and a given finger's total junction (or device) temperature results from self-heating and thermal coupling.

This thesis presents physics-based scalable compact modeling frameworks for static thermal coupling, extraction, and modeling of the total finger (or junction) temperatures in multi-finger transistors for actual operating conditions. Our framework applies to multi-finger structures without and with shallow and deep trench isolations and accounts for heat-flow through Back-End-of-Line (BEOL) metal layers. This work requires no additional measurements than the state-of-the-art self-heating and thermal coupling characterization. For validation purposes, we have presented model agreement with 3D-TCAD simulations and have implemented the model for on-wafer transistors with different emitter geometries fabricated on state-of-the-art process flow of STMicroelectronics and IHP Microelectronics.