The seed crystal used for czochralski crystal growth is necked down to about 3 mm diameter to produce a dislocation-free crystal. use 2 x 10^6 g/cm2 as the yield strength of silicon at the growth temperature (the units are strange but correct assuming the gravitational constant of earth, etc.) and determine the maximum length of each ingot that can be supported by this neck if the ingots are 150, 200 and 300 mm diameter.
for the 200 mm diameter case, how many wafers can be produced (if the final wafer thickness is 725 mm).