model predictive control in semiconductor

**MPC** (Model Predictive Control) in semiconductor manufacturing is a **multi-variable control strategy that uses a process model to predict future outputs and optimize control actions over a prediction horizon** — considering constraints, interactions between variables, and future setpoint changes. **How Does MPC Work in Fab?** - **Process Model**: A dynamic model predicts how process outputs respond to input changes over time. - **Prediction Horizon**: Predict output trajectories several time steps ahead. - **Optimization**: At each step, solve an optimization problem to find the control inputs that minimize future error. - **Constraints**: Explicitly handles input constraints (power limits, flow ranges) and output constraints (spec limits). **Why It Matters** - **Multi-Variable**: Handles coupled, interacting process variables better than independent SISO controllers. - **Constraint Handling**: Respects physical process limits while optimizing performance. - **Thermal Processes**: Particularly effective for furnace and thermal CVD processes with slow dynamics and interactions. **MPC** is **chess-playing process control** — looking multiple moves ahead to find the optimal control strategy while respecting all constraints.