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

摘要

Cast-mono crystalline silicon (CM-Si) wafer is a new promising material for thefabrication of silicon solar cells. This study demonstrates the characteristics anddistribution behaviors of microdefects in the damaged layer of CM-Si waferinduced by slurry sawing using the transmission electron microscopy (TEM)method. It is found that a large number of stacking faults and dislocations areformed around the sharp kerfs caused by the indenting effect of sharp grits,which is associated with the release of remaining stress after the propagation ofmicro cracks. Meanwhile, amorphous silicon phase appears in the round kerfregion induced by round grits, without any crystalline defects around. It indicatesthat plastic deformation is an important way to release the strain in the brittlesilicon material during slurry sawing. In addition, nano cracks coated with siliconO_xide layer and originated from the piling-up of dense edge dislocations can beobserved beneath the smooth surface of slurry-sawn wafers. These results helpus better to understand the generation mechanism of microdefects during slurrysawing process.