Test wafer control system in 300 mm FAB

Test wafers are used in wafer fabrication to monitor equipment stability and product quality. Any shortage causes the loss of equipment capacity and production move. On the contrary, to prepare more test wafers to avoid shortage spends more cost, occupies more storage space, and lowers transfer efficiency. Considering the wafer cost and FAB productivity, an efficient control system of test wafer in 300 mm FAB is much more important than formerly.