Analysis of stress intensity factors and T-stress to control crack propagation for kerf-less spalling of single crystal silicon foils

Abstract : Monocrystalline silicon (called mono silicon) is extensively used in the electronic and solar photovoltaic industries. During the last decade, many new manufacturing processes have been developed to improve solar cells' efficiency while reducing their cost of production. This paper focuses on a kerf-less technique based on the controlled fracture of silicon foils by depositing an adherent stress-inducing layer on {hkl} cleavage plans. A finite element model (FEM) is defined to study the stress intensity factors (SIFs) associated with a pre-crack located at a certain depth from the interface between the silicon substrate and the stress-inducing layer. A parametric study elucidates the dependence of the crack propagation direction on process variables including thickness of the stress-inducing layer, silicon substrate thickness, and pre-crack depth. The use of stress intensity factors and the T-stress characterize the crack propagation. These results are essential for efficient control of this kerf-less spalling process.