YieldWatchDog
SPATIAL SIGNATURE CONTROL MODULE
The Spatial Signature Control (SSC) Module allows monitoring and early
detection of equipment specific spatial signatures among wafer test data.
Long before equipment-characteristic spatial signatures are visible on wafer
bin maps, they can be detected by the SSC Module, which looks closely on the
spatial distributions of the underlying parameters.
Thus, specific tool degradations can be detected at an early stage, enabling
timely counteraction.
Development of a ring-shaped signature on wafer maps of 60 lots, including
noise. While the human observer may notice the signature at about lot #50, the
SSC Module detects it at lot #20.
