(111)Si thin layers detachment by stress-induced spallation

Abstract

In this work, results of controlled detachment of (111) silicon by stress induced spalling (SIS) process, which is based on a gluing on a metallic stressor layer by an epoxy adhesive on top of a silicon substrate, are presented. It is shown that silicon foils mainly (1 × 1) cm2 with different thicknesses (~50–170 µm) can be successfully detached using different materials (steel, copper, aluminum, nickel and titanium) as stressor layers with thicknesses ~50–500 µm. Such detachment can be realized by dipping of a stressor/glue/silicon wafer based structure into liquid nitrogen. As a result, Si foils with different thicknesses from ~50 µm to ~170 µm can be detached. An analytical and numerical approaches based on principles of linear elastic fracture mechanics is developed and they are shown that such approaches can predict general trends and conditions for the detachment of silicon foils with desired thicknesses using a stressor layer. Raman spectroscopy analysis of the residual stresses in detached silicon foils shows, that tensile stresses (up to −36 MPa) as well as higher value compressive stresses (up to ~444 MPa) are present in such foils. Moreover, optical and scanning electron microscopy (SEM) measurements show that surface of the detached foils exhibits some periodic lines originated by stresses.