Microdefect Characteristics in Cast‐Mono Silicon Wafers Induced by Slurry Sawing

Abstract

Cast‐mono crystalline silicon (CM‐Si) wafer is a new promising material for the fabrication of silicon solar cells. This study demonstrates the characteristics and distribution behaviors of microdefects in the damaged layer of CM‐Si wafer induced by slurry sawing using the transmission electron microscopy (TEM) method. It is found that a large number of stacking faults and dislocations are formed around the sharp kerfs caused by the indenting effect of sharp grits, which is associated with the release of remaining stress after the propagation of micro cracks. Meanwhile, amorphous silicon phase appears in the round kerf region induced by round grits, without any crystalline defects around. It indicates that plastic deformation is an important way to release the strain in the brittle silicon material during slurry sawing. In addition, nano cracks coated with silicon oxide layer and originated from the piling‐up of dense edge dislocations can be observed beneath the smooth surface of slurry‐sawn wafers. These results help us better to understand the generation mechanism of microdefects during slurry sawing process.