hot lot processing

**Hot lot processing** is the **expedited handling mode that elevates selected lots above normal dispatch priority to meet urgent business or engineering deadlines** - it accelerates specific lots but can disrupt overall fab flow if overused. **What Is Hot lot processing?** - **Definition**: Priority class with dispatch, transport, and scheduling privileges beyond standard lots. - **Acceleration Mechanisms**: Queue bypass, protected transport, setup preemption, and immediate dispatch preference. - **Use Cases**: Customer expedites, yield-critical diagnostics, qualification gates, and recovery from delays. - **Governance Need**: Requires strict eligibility and approval controls to prevent priority inflation. **Why Hot lot processing Matters** - **Deadline Recovery**: Enables urgent commitments to be met when normal flow would miss due dates. - **Engineering Agility**: Speeds critical learning loops during issue resolution. - **System Tradeoff**: Frequent hot-lot overrides increase waiting for standard lots and can raise global cycle time. - **Operational Fairness**: Uncontrolled use degrades dispatch discipline and planning credibility. - **Performance Balance**: Hot-lot benefit must be weighed against total fab throughput impact. **How It Is Used in Practice** - **Eligibility Rules**: Define approved trigger criteria and maximum hot-lot share limits. - **Priority Orchestration**: Coordinate AMHS, stocker, and tool-dispatch behavior for expedited lots. - **Impact Review**: Track collateral delay and adjust hot-lot policy to protect overall flow health. Hot lot processing is **a necessary but high-cost scheduling exception** - controlled use delivers urgent responsiveness while preserving broader fab performance and queue stability.