Comparative analysis of modeling and experiments to study spalling process in Si wafers

Abstract

A comparative analysis including modeling and experimental evaluation of a spalling process of silicon (Si) substrates was accomplished to define the optimum condition for uniform spalling. The residual stresses in Nickle (Ni) films on Si substrates have been evaluated. Different thicknesses of Ni films electroplated on Si(100) and Si(111) substrates have been used to predict the steady-state spalling depth and crack propagation direction. This study focuses on identifying the key variables; including the Ni film thickness (h) and critical stress needed to peel-off uniform thin layers from a Si substrate. The residual stresses (thermal and epitaxial) in the Ni films have been evaluated through experiment and modeling analysis to distinguish the sources of stress generation. Different thicknesses of spalled films from Si substrates were defined to investigate the influence of the stress intensity factors (KI, KII and KIII) and the energy release rate (J1) on the steady state spalling process. Finally, the critical normal stress (σII) versus h has been determined to predict the spalling depth with uniform thickness.