Subsurface Damage of Monocrystalline Germanium Wafers by Fixed and Free Abrasive Lappings

The subsurface damage （SSD） layers of monocrystalline germanium wafers lapped by three different ways were measured and compared by the method of nanoindentation and micro morphology. Three ways such as ice-fixed abrasive, thermosetting fixed abrasive and free abrasive lappings are adopted to lap monocrystalline ger manium wafers. The SSD depth was measured by a nanoindenter, and the morphology of SSD layer was observed by an atomic force microscopy（AFM）. The results show that the SSD layer of monocrystalline germanium wafer is mainly composed of soft corrosion layer and plastic scratch and crack growth layer. Compared with thermosetting fixed abrasive and free abrasive lappings, the SSD depth lapped with ice fixed abrasive is shallower. Moreover, the SSD morphology of monocrystalline germanium wafer lapped with ice fixed abrasive is superior to those of two oth- er processing ways.