wafer sorting / binning

Wafer sorting and binning classifies wafers or individual dies based on electrical test results into categories reflecting their quality, speed, or functionality. **Wafer sort (probe)**: Test every die on wafer at probe station before dicing. Identify good and bad dies. Mark bad dies with ink dot or in electronic map. **Die binning**: Classify each die into bins based on test results. Bin 1 = fully good. Other bins = partial good, speed grades, or fail categories. **Speed binning**: Dies that pass all functional tests but at different speeds sorted into performance grades (fast, typical, slow). Different bins may be sold as different products. **Yield**: Wafer sort yield = (good dies / total dies) * 100%. Primary manufacturing metric. **Test program**: Automated test program applies test vectors, measures responses, and classifies each die per bin criteria. **Probe card**: Array of tiny probes contacts die bond pads simultaneously. Must align precisely to pad locations. **Parametric testing**: During sort, parametric measurements (Vt, Idsat, leakage) collected for statistical process monitoring. **Pass/fail criteria**: Specifications define limits for each test. Any out-of-spec measurement assigns die to fail or downgrade bin. **Ink marking**: Traditional method to physically mark bad dies. Modern fabs use electronic wafer maps instead. **Multi-site probing**: Test multiple dies simultaneously for throughput. 4-32 sites common. **Cost**: Wafer sort testing significant cost component. Test time per die x number of dies = total test cost.