process defects

**Process defects** is the **quality loss category where processed wafers fail to meet specification and become scrap, rework, or hold material** - it directly reduces quality rate and increases manufacturing cost. **What Is Process defects?** - **Definition**: Nonconformances introduced during processing, including dimensional, electrical, contamination, or structural failures. - **Defect Sources**: Equipment instability, recipe drift, material variation, and handling anomalies. - **Disposition Outcomes**: Scrap, rework loops, engineering hold, or downgraded product value. - **OEE Role**: Counted in quality losses as bad units from available and running equipment. **Why Process defects Matters** - **Economic Loss**: Defective wafers carry full accumulated process cost before value is lost. - **Yield Risk**: Defect excursions can rapidly propagate across lots if detection is delayed. - **Capacity Waste**: Tool time spent producing defects displaces productive output. - **Customer Impact**: Persistent defect modes threaten delivery and reliability commitments. - **Improvement Priority**: Defect prevention usually has high leverage in OEE and margin programs. **How It Is Used in Practice** - **Defect Taxonomy**: Classify defects by type, layer, tool, and probable origin. - **Rapid Containment**: Trigger hold and investigation protocols when defect thresholds are exceeded. - **Permanent Correctives**: Link root-cause closure to recipe controls, maintenance, and contamination management. Process defects is **a primary quality and profitability risk in semiconductor manufacturing** - sustained defect reduction is essential for high-yield, high-OEE operations.