how does a film defect affect die yield

YIELD = the fraction of good die out of the total on a wafer. A FILM DEFECT can kill yield in two ways: 1) A KILLER DEFECT (like a particle, a void, a delamination) lands on or within a die and makes that die FAIL → that die is lost (a 'killer defect'). 2) A defect can cause a PARAMETRIC shift (film too thick/thin → transistor too slow or leaky) → the die may fail a performance spec. So a film quality problem directly = fewer good die = money lost. WHY GPS CARES: a customer complaint about yield is usually traced back to a process or film problem — that's the GPS job (Lesson 70). The one-line frame: 'A film defect becomes lost die — every particle or void can be a dead die, and even a thickness shift can fail performance, so film quality is yield.' It ties your technical depth to the business impact the panel cares about.