Yield is good output divided by input, stated per step or end to end. Fabs track line yield (wafers surviving the process), die or sort yield (good die per wafer at probe) and final test yield, and multiply them for overall yield. Rolled throughput yield multiplies first-pass yields across every step, so ten steps at 98 percent each give only about 82 percent, which exposes rework that a final yield figure hides.
Sort yield on the new product is stuck at 71 percent and the wafer maps all show the same edge ring.
Always ask which yield. Line, sort, final test and rolled throughput figures for the same product can differ by tens of points.
Related terms
Defect density
Number of yield-killing defects per unit area of wafer or panel, the main input to yield models.
Wafer map
Picture of a wafer showing each die's test result or measurement by location, used to spot spatial failure patterns.
Bin
Test category that each die or unit is sorted into at probe or final test, with bin 1 usually meaning good.
Killer defect
Defect that lands where it causes a die to fail, as opposed to a harmless cosmetic or nuisance defect.
DPMO
Defects per million opportunities: defect count scaled by the number of chances for a defect in each unit.