Excursion is fab and plant shorthand for an abnormal event that moves a metric well outside its usual band, such as a particle spike on one tool, a yield drop on a group of lots or a parameter jump after a chemical change. Excursions start a familiar routine: hold affected material, define the scope, run commonality analysis across tools and steps, fix the cause and disposition the held lots. Teams track excursion count and lots affected as a key metric.
We're calling it an excursion: 14 lots through etcher 6 since Thursday, all with the same bin 9 signature.
The first hour of an excursion is about scope, not cause: find every lot that touched the suspect tool before anyone starts theorizing.
Also heard as
- yield excursion
- defect excursion
- yield bust
Related terms
Special cause
Specific, identifiable source of variation that is not part of the process's normal behavior and shows up as a chart signal.
Killer defect
Defect that lands where it causes a die to fail, as opposed to a harmless cosmetic or nuisance defect.
Wafer map
Picture of a wafer showing each die's test result or measurement by location, used to spot spatial failure patterns.
OOC
Out of control: shorthand for a point or chart that has violated a control limit or run rule.