What is Die-Level Burn-in and Test?

IC manufacturers are creating more expensive package designs and multi-chip module (MCM) packages to deliver increased packaging density. MCMs contain several individual die in each package. Presently, burn-in and test are performed after the die are assembled into the module. Manufacturers realize that repairing or discarding a defective MCM is far too costly. As a result, die level burn-in and test of the individual die (before packaging) ensures that they only package known-good die (KGD) and, in turn, produce a quality product at a reduced cost.