reduced speed

**Reduced speed** is the **performance loss that occurs when equipment runs below its validated ideal cycle rate during available production time** - the tool is running, but not at intended throughput. **What Is Reduced speed?** - **Definition**: Gap between actual run rate and reference standard run rate under normal conditions. - **Typical Drivers**: Mechanical wear, conservative parameter settings, handling delays, and control-loop drift. - **Measurement Basis**: Compare observed cycle time against product- and recipe-specific ideal standards. - **Loss Behavior**: Usually gradual and persistent rather than abrupt like failure downtime. **Why Reduced speed Matters** - **Capacity Erosion**: Speed losses reduce output even when availability appears healthy. - **Cost Increase**: Lower throughput raises fixed-cost burden per wafer. - **Masking Risk**: Slow deterioration can go unnoticed without strong rate monitoring. - **Planning Distortion**: Schedules based on ideal rates become unreliable when derating persists. - **Continuous Improvement Value**: Restoring speed often has rapid return on engineering effort. **How It Is Used in Practice** - **Rate Baselines**: Maintain updated ideal-cycle standards by product family and tool type. - **Gap Analysis**: Investigate sustained speed variance by subsystem and operating condition. - **Corrective Actions**: Apply servo tuning, preventive replacement, and recipe optimization. Reduced speed is **a major performance drain in mature production systems** - recovering lost run rate is one of the fastest ways to improve output without added equipment.