Effects of carbide and nitride inclusions on diamond scribing of multicrystalline silicon for solar cells

Single grit diamond scribing experiments were carried out to understand the effects of SiC and Si3N4 inclusions in diamond wire sawing or cutting of photovoltaic multicrystalline silicon (mc-Si) substrate material. Results show that hexagonal rod-type Si3N4 inclusions can significantly increase the cutting force and lead to large scale localized brittle fracture of the mc-Si substrate. In contrast, SiC filament-type inclusions do not affect the scribing/cutting process. Si3N4 fibers are found to be flexible and are not cut by diamond scribing. Explanations for the observations are given based on the material properties of mc-Si, diamond and inclusions. The detrimental effects of SiC and Si3N4 inclusions on diamond wire sawing are also discussed.