Mécanique de la rupture dans les cristaux fonctionnels

Abstract

Silicon, a semiconductor material, is at the core of modern technological advancements, particularly in electronics, microelectromechanical systems (MEMS), and solar cells. Its crystalline structure and mechanical properties make it a material of choice for numerous applications. However, its intrinsic brittleness and sensitivity to crack propagation pose significant challenges, especially under demanding operational conditions where thermal and mechanical stresses can compromise device reliability. Understanding the fracture mechanisms of silicon, particularly under the influence of doping and temperature, is therefore crucial for improving the durability and performance of electronic components. This study investigates the anisotropic fracture behavior of boron-doped single-crystal silicon as a function of temperature and crystallographic orientation. Using Vickers indentation tests conducted between 25°C and 90°C, we analyze the evolution of fracture toughness, fracture energy, and hardness. The results highlight strong anisotropy, with maximum fracture energy in the [100] orientation and a minimum in the [110] orientation, suggesting preferential crack propagation in the latter direction. Additionally, increasing temperature leads to a progressive decrease in mechanical properties. In this study, boron-doped silicon exhibits a distinct fracture behavior compared to undoped silicon. Unlike previous observations on pure silicon, where fracture toughness increases with temperature due to dislocation activation, our results suggest that boron doping limits dislocation mobility and thereby contributes to the reduction of fracture energy at elevated temperatures. These findings are essential for the design and durability of silicon-based electronic components. However, further research is needed to better understand the effects of dopants on silicon fracture by integrating additional analytical methods.

Date	13 Mar 2025
Original language	French
Awarding Institution	École de technologie supérieure
Supervisor	Ricardo J. Zednik (Supervisor)