Characterization of Atomic-Layer-Deposited (ALD) Al2O3-Passivated Sub-50-mu m-thick Kerf-less Si Wafers by Controlled Spalling

Abstract

A systematic characterization of sub-50-mu m-thick, kerf-less monocrystalline Si wafers fabricated by a controlled fracture method is presented. The spalling process introduces various defects on the Si surface, which result in high surface roughness levels, residual stress, and low effective minority carrier lifetimes. In addition, metals used to induce fracturing in Si diffuse in the Si at room temperature and degrade the effective minority carrier lifetime. Selective removal of these defected Si regions improves the residual stress and effective lifetimes of spalled Si wafers.