wafer map

**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.