BONDING SUBSTRATE SURFACE DEFECT EVALUATION METHOD

The present invention provides a method for evaluating surface defects of a substrate to be bonded, including the steps of: preparing a mirror-polished silicon single crystal substrate; inspecting surface defects on the mirror-polished silicon single crystal substrate; depositing a polycrystalline silicon layer on a surface of the silicon single crystal substrate subjected to the defect inspection; performing mirror edge polishing to the silicon single crystal substrate having the polycrystalline silicon layer deposited thereon; polishing a surface of the polycrystalline silicon layer; inspecting surface defects on the polished polycrystalline silicon layer; and comparing coordinates of defects detected at the step of inspecting the surface defects on the silicon single crystal substrate with counterparts detected at the step of inspecting the surface defects on the polycrystalline silicone layer and determining quality of the silicon single crystal substrate having the polycrystalline silicon layer as a substrate to be bonded on the basis of presence/absence of defects present at the same position. Consequently, there is provided the method for evaluating surface defects of a substrate to be bonded which enables rationally avoiding a reduction in manufacturing yield of the substrates to be bonded and decreasing a void defect occurrence ratio after bonding.