Characterization of wafer shape after grinding with diamond wheel

Subsurface damage is formed in the silicon wafer during the thinning process,where residual stress causes defects.Therefore,variation law of the warping profile was studied in the silicon wafer without spark-out process.The silicon wafers were thinned to 400μm or 450μm by a diamond grinding wheel and their warping profiles were measured.The silicon surface profile was divided into five rings from the center to the edge in radial direction and the radius of curvature of each area was obtained by spherical fit respectively.By analyzing the warping profile,it is found that the deformation of the silicon wafer increases from the central area to the edge and it implies that the residual stress grows and so does the grinding damage.In addition,it is found that the crystal orientation has a significant effect on the deformation of silicon wafer,thus the deformation in the 〈110〉crystal orientation area quite different from that in the〈100〉crystal orientation area.