Wafer map is a visual representation of die pass/fail status — color-coded map showing which dies on a wafer passed or failed testing, the primary tool for identifying systematic defects and process issues.

What Is Wafer Map?

• Definition: Spatial visualization of die test results on wafer.
• Display: Grid showing each die, color-coded by status.
• Purpose: Identify patterns, locate defects, diagnose issues.

Color Coding: Green/pass (good die), red/fail (bad die), yellow/marginal (borderline), gray/untested (edge dies).

What Wafer Maps Reveal

Spatial Patterns: Center-to-edge gradients, quadrant effects, radial patterns. Systematic Defects: Repeating patterns indicate process issues. Random Defects: Scattered failures from particles. Equipment Issues: Patterns correlate with process tools. Reticle Defects: Repeating patterns at reticle step size.

Pattern Types: Center hot/cold (CMP, implant), edge effects (etch, deposition), quadrant effects (equipment), radial patterns (spin coating), repeating patterns (reticle, stepper).

Applications: Yield analysis, defect diagnosis, process monitoring, equipment qualification, root cause analysis.

Tools: Wafer map visualization software, statistical analysis tools, pattern recognition algorithms.

Wafer maps are window into manufacturing — revealing spatial patterns that guide engineers to root causes of yield loss.