Research on stress and subsurface damage on silicon wafer machined by rotational grinding

The stress condition of local area in a wafer is acquired.By measuring the flatness of local area in the tested wafer,the planar principal stresses and their directions are solved using inverse calculation.The analysis result based on diamond ground(100)silicon wafer shows that the stress condition at different locations on the wafer does not consist well with the average stress solved by conventional methods using Stoney's equation.The stress condition depends on its location on the wafer.Moreover,taper polishing is adopted to test the depth of subsurface damage,which reveals that the depth of damage layer is about 0.4 μm with various condition and there are no distinct relationships between machining stress and subsurface damage.