it's not a chipmaking factory. what they are doing in there is post-silicon device verification. when you design one of these chips, the timing parameters for the process are good to a junction temperature of, say, 85C and down to 0C. if you make it colder or hotter than this, it can and will malfunction. so what they are doing here is checking to make sure the packaged silicon matches the timing parameters that were used when the chips were taped out by heating and cooling the die. usually there is some margin designed in, and the process varies as well, so you end up with fast silicon, slow silicon and typical silicon. they change the temperature, voltage and clock rates to explore that whole space and characterize the silicon that TSMC gives to them.
usually they also need to verify the whole system at hot and cold temperatures as well. but here, since they had a heater/cooler applied to the chip only, they must be interested in how the SoC device itself reacts to temperature changes.
