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May 2, 2012

Wafer Edge Inspection and Metrology

This inspection process focuses on the area near the wafer edge, an area that poses difficulty for traditional frontside inspection technology due to its varied topography and process variation. This inspection step is implemented during ADI, post-etch, post-clean and post-CMP.

Typical defects include:

  • Peeling films
  • Residual slurry or photoresist
  • Cleaning contaminants
  • Residual films
  • Surface and embedded defects
  • Edge Bead Removal and Bevel Clean metrology

Partial Patterned and Edge Exclusion Defect Inspection (Edge Top)
Edge top inspection is aimed at identifying contamination in the partial patterned and edge exclusion area that signifies other process problems.

Edge Bevel Inspection (Edge Normal)
Edge bevel inspection focuses on the side edge of a wafer to determine if it has any chips, cracks, contamination or layering delamination. Edge Bevel Inspection can be implemented at any point throughout the wafer manufacturing process.

Edge Bead Removal (EBR) and Bevel Clean Metrology
This topside and bevel surface measurement is required in multiple process, primarily to determine if wafers have been properly aligned for cleaning or for the creation of the edge exclusion region. This edge film boundary measurement is required exclusively in the photolithography process.  This process also verifies that the EBR and bevel clean process worked as intended. EBR metrology measures the distance from the wafer apex to the edge of the resist film at up to 360 points around the wafer circumference. Bevel clean metrology measures the distance from the wafer topside to the film boundary at up to 360 points around the wafer circumference.