there are even simpler problems. in the factory I worked in 25 years ago they changed their line from 6" wafers to 8" wafers. as the wafers were significantly larger they now had the problems of sliplines as the support for the wafers induced now stress on the wafers, the wafers being not only larger but heavier too. now imagine these heterostructures you have now on dimensions many orders of magnitude smaller than then and the wafer sizes are even bigger