Wafer Map Analyzer

A wafer map is a confession. The failing dies don't scatter at random when something is wrong — they arrange themselves into shapes, and each shape names a culprit. A bright cluster in the center says the chuck or a center-fed process; a ring at the rim says edge-bead, coating non-uniformity, or a handling clamp; a straight line says a robot arm dragged across the surface. Before any deep analysis, the shape itself is the first and often decisive clue.

The most important call comes first: is the pattern random or systematic? Uniformly scattered defects mean particles — contamination to be driven down by cleanliness, with no single tool to blame. A spatial signature means a specific, repeatable cause is at work, and the investigation should hunt for the responsible step or equipment rather than chase dust. Getting this split right sets the entire direction of the root-cause effort, and the radial-zone breakdown here is built to make it obvious.

The edge deserves special mention because it loses yield for reasons all its own — processed differently from the center in many tools, touched by handling, prone to coating and deposition non-uniformity. Some edge loss is expected and absorbed by edge-exclusion, but a strong, clear edge ring beyond that baseline is a fixable problem announcing itself, and distinguishing the two is exactly what the edge-zone rate is for.

Fabs scale this intuition with signature libraries — catalogs of known patterns mapped to causes and corrective actions — so a new map can be auto-classified and routed without manual reading. This tool is a hands-on version of that logic: pick a pattern, see the map, and watch the signature resolve to a likely cause. Then quantify which defect categories dominate in the Root Cause Finder and the yield hit in the Defect Density console.