discrete event simulation

**Discrete Event Simulation (DES)** in semiconductor manufacturing is a **simulation methodology that models fab operations as a sequence of events occurring at discrete time points** — processing arrivals, tool completions, breakdowns, and lot dispatching to predict cycle time, throughput, and tool utilization. **Key DES Components** - **Events**: Lot arrival, process start, process end, tool breakdown, PM start/end. - **Queues**: Lots waiting at each tool group with dispatching priority rules. - **Resources**: Tools (with availability, PM schedules), operators, transport vehicles. - **Statistics**: Collect cycle time, WIP, utilization, queue time distributions during simulation. **Why It Matters** - **Capacity Planning**: Determine how many tools are needed for a target throughput and cycle time. - **What-If**: Test the impact of tool additions, recipe changes, or product mix changes before implementation. - **Industry Standard**: Tools like Applied Materials AutoSched, Rockwell Arena, and AnyLogic are widely used in fab planning. **DES** is **fast-forwarding through the fab** — simulating months of factory operations in minutes to optimize capacity, scheduling, and throughput.