batch wait time

**Batch wait time** is the **time earliest lots spend waiting for additional compatible lots before a batch tool starts processing** - this formation delay can be a major hidden contributor to cycle time. **What Is Batch wait time?** - **Definition**: Elapsed delay between first lot arrival to batch queue and batch launch. - **Formation Drivers**: Batch-size thresholds, compatibility constraints, and arrival variability. - **Distribution Behavior**: Early-arriving lots in each batch typically experience the highest wait. - **Control Link**: Strongly affected by dispatch, release pacing, and batch-start policy. **Why Batch wait time Matters** - **Cycle-Time Inflation**: Long formation waits can dominate total lead time at batch steps. - **Queue-Time Risk**: Excessive waiting may threaten sensitive process windows. - **Delivery Variability**: Uneven wait patterns increase completion-time uncertainty. - **Efficiency Tradeoff**: Reducing wait may lower fill rate, requiring balanced policy design. - **Bottleneck Health**: High batch wait indicates mismatch between arrival flow and launch rules. **How It Is Used in Practice** - **Wait Monitoring**: Track average and tail formation delay by recipe and tool. - **Policy Controls**: Apply max-wait thresholds and dynamic launch triggers. - **Flow Alignment**: Coordinate upstream dispatch so compatible lots arrive in tighter windows. Batch wait time is **a critical controllable component of batch-tool performance** - managing formation delay is essential for reducing cycle time while maintaining acceptable utilization.