What is SIRD
SIRD is Scanning Infra-Red Depolarization. SIRD measures stress in optically transparent materials utilizing a non-contact and non-destructive technology for:
--Si wafers up to 300mm
--Compound materials
--Solar cells
Why SIRD needed
Reason is Stress will be caused by any abrasive manufacturing or temperature-related process step during the manufacture of wafers as well as in IC fabs. Small defects cause a much larger Stress area. Even defects near the edge propagate deep into the wafer Analytical operations reveal the actual defect together with its true location.
How SIRD execute stress measurement
Bare wafer measurement sample
Global defects
Big ring like patterns probably caused by non-uniformities of dopant or impurity concentration
Local defects distribution:
Differential Depolarization / High-pass filtered
Defects distribute in different place on wafer
