The fracture strength of nitrogen doped silicon wafers
With a specially designed double ring bending setup, we have studied the ro om temperature fracture strength of silicon wafers prepared by standard manufacturing methods with both (as) cut, (as) lapped. and (as) polished surfaces. Wafers from six different crystals have been tested, The differences between these crystals are related 10 growth method (float zone or Czochralski), concentration of light element impurities (nitrogen and oxygen). and further processing (neutron irradiation and thermal annealing), No significant differences in strength between crystal of different origin ean be revealed on wafers prepared with (as) cut and (as) lapped surfaces, Polished wafers generally show a fraeture strength of the order of l GPa, with a large scatter between single measurements. o differences between the strength of polished wafers from float zone (FZ) and Czochralski (CZ) crystals ean be detected, but the median strength of a FZ crystal with small concentration of both nitrogen and oxygen is observed to have a much higher value of 2.5 GPa.