Electro-thermo-mechanically coupled simulation of actively heated silicon chips

Abstract

In this thesis the current FEM simulation methodology regarding a polyheater, used as test device for thermo-mechanical reliability analysis of power metallizations, was investigated in order to verify its usage. In addition, the errors associated with various simplifications compared to a fully coupled simulation are estimated. Thermal simulations of the current FEM models were performed in order to demonstrate the significance of each distinct heat transfer method and its combinations. A simple 2D composition of thin films is constructed to see and learn how numerical contact mechanics work in our FEM development environment. Building upon this a 2D model of the 511 polyheater is assembled to simulate electrothermo-mechanical behaviour due to the voltage pulses of the measurements. Different approaches to simulate the full heat capacity of the 3D model in a 2D environment are conducted and compared with the focus on the different heat dissipation mechanisms. Uncoupled thermo-electrical simulations are compared to fully coupled electro-thermo-mechanical simulations. This comparison shows, that with the used material models and the perfectly smooth layers of the model, decoupled thermo-electrical simulations have a better cost-benefit ration than fully coupled electro-thermo-mechanical simulations.