Essential Guide to Semiconductors, The

Bringing Out the Diamonds

Assuming that at least some chips pass inspection and the entire wafer isn't bad, all the chips will be cut apart using a diamond-bladed saw. The stepper leaves a bit of space between each chip as it moves left to right and top to bottom. This blank area allows the saw to carefully cut in between the chips without damaging them. The diamond saw is very thin, as you might imagine, and is designed to kick up a minimum of “silicon sawdust.” Contaminating an entire wafer at this late stage would be economically unpleasant.

After the chips are cut apart, the good chips are sorted from the bad chips by a robot that searches for the tell-tale red dot. Also, the cut-off fringes of the round wafer are discarded like high-tech ...