Samer1970 :
and why not just cut the wafer into small rectangles before printing? the size that gives good yield ? having better yield will cover the cost of the unused cut wafer .. because you can cut the rectangles to the size point you get almost perfect yields .. who cares about some unprinted small cut edges when everything inside will yield perfectly?
If you mean cutting dies before the circuit is assembled on the silicon, that makes absolutely no sense since it would increase the number of processing and handling steps a hundred fold.
If you meant making square silicon ingots and aligning the die pattern to fit the most dies on that, this does not work either. Do you know why wafers are circular? Because the ingots are grown from a seed and grows radially from there. If you wanted a square ingot, you'd have to carve it out of a cylindrical one.
The other reason why round wafers are used is because the silicon chip fabrication process involves high temperatures and a round wafer distributes thermal expansion stresses evenly radially across the wafer which minimizes stresses and warping. A square wafer would have uneven stresses and more uneven warping, which would make the process of aligning the wafer within nanometers between processing steps even harder than it already is with deformations that may be impossible to compensate for.
If there was a more cost-effective way to make chips, Intel, TSMC, UMC, GloFo, etc. would be all over it. Right now, the next wafer cost reduction technology is lined up to be 450mm wafers.