Abstract
KOH anisotropic etching is used to study the interfaces of bonded silicon wafers. This method has been developed to detect the presence of bubbles or unbonded areas with a gap of less than 0.27 µm, which is the detection limit of an IR camera. Because of the anisotropic etching properties of KOH and the presence of interfacial oxide layers, the etching surface morphology is dependent on the crystallographic orientation of the cross section. Correlation of etching results to the bonding strength of silicon wafers with and without a thermally oxidized silicon layer is also discussed.