ATE (automatic test equipment)
Beginner
The big, expensive machine in the factory that plugs into each chip, runs the tests and sorts good from bad.
Novice
The factory tester. Under the control of a test program, it applies stored patterns to a chip through its pins, compares the responses with the expected values and marks the chip good or bad, either on the wafer or after packaging.
Expert
Cost scales with channel count, speed, pattern memory and instruments, so DFT aims to cut the channels needed (compression), pattern memory and test time, and to let one tester test several chips at once (multi-site).
Explained in Design for test (Design Flow).
See also: Wafer sort (probe test), Final test (package test).