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.