Uph (units per Hour)

Units per hour (UPH) measures wafers or lots processed per hour, quantifying tool or process step throughput in semiconductor manufacturing. Calculation: UPH = (Wafers processed) / (Production time in hours). Related metrics: (1) Cycle time per wafer (seconds/wafer = 3600/UPH); (2) Lots per hour; (3) Wafer starts per week (WSPW—fab-level). UPH components: actual process time + wafer handling time + overhead (alignment, pump/vent, chamber transfer). UPH by tool type: (1) Steppers: 100-300 WPH depending on layers; (2) Etch: 20-80 WPH depending on process; (3) CVD: 15-50 WPH depending on film thickness; (4) Furnaces: variable (batch tool, 50-200 wafers at once). UPH improvements: reduce handler time (faster robots), parallel processing (multi-chamber tools), recipe optimization (shorter process time if within spec), eliminate waits (better scheduling). Bottleneck impact: UPH of bottleneck tool directly limits fab capacity. Capacity planning: Required tools = (WSPW × cycle time) / (Available hours × UPH × utilization). UPH vs. quality: increasing UPH may impact process quality—must validate. Monitoring: MES tracks wafer events, calculates real-time and historical UPH. Critical for capacity planning, bottleneck identification, and continuous improvement targeting.