Fabrication Simulation Model for Semiconductor Lot Priority Adjustment
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Solution Overview
Problem
Current Manufacturing Execution Systems (MES) in semiconductor fabrication rely heavily on manual intervention for determining lot priorities, leading to disruptions in production flow, increased cycle times, and reduced tool utilization due to the limited availability of bottleneck tools for high-priority lots, which affects overall throughput and production efficiency.
Innovation Solution
A method and system utilizing a fabrication simulation model to dynamically adjust lot priorities based on a comparison between target and estimated completion times, implemented through a priority analyzer that simulates the processing of workpieces across multiple operations, ensuring optimal priority assignment and minimizing the impact on other lots.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If manual intervention is used to determine lot priorities in MES, then flexibility in priority adjustment is improved, but production flow stability deteriorates and cycle time increases
Solution Approach 1:
The system implements automatic feedback loops where the simulation model continuously monitors lot progress and tool status, then adjusts priorities based on real-time conditions. This replaces manual intervention with an automated system that senses production state and responds with priority adjustments, maintaining flexibility while stabilizing production flow through consistent, rule-based decision-making.
Solution Approach 2:
The MES system performs self-adjustment of lot priorities through the simulation model without requiring manual intervention. The system serves itself by automatically detecting when priority changes are needed and implementing those changes based on simulated outcomes, thereby maintaining adaptability while eliminating the instability introduced by human operators.
2Loss of time
If high-priority lots are expedited through manual priority changes, then completion time for specific lots is improved, but tool utilization deteriorates and overall throughput decreases
Solution Approach 1:
The system dynamically adjusts lot priorities based on real-time simulation of production conditions rather than static manual assignments. Priority levels change adaptively as the simulation model evaluates current tool availability, work-in-progress status, and delivery requirements, allowing the system to optimize both completion time and tool utilization under varying conditions without manual intervention.
Solution Approach 2:
The simulation model evaluates multiple parameter combinations (priority levels, tool reservations, scheduling options) to determine the optimal configuration that balances expedited lot completion with overall tool utilization. By systematically varying and evaluating these parameters through simulation, the system identifies solutions that minimize completion time for high-priority lots while maintaining acceptable tool utilization levels.
3Loss of time
If bottleneck tools are reserved for high-priority lots, then delivery time for urgent lots is improved, but overall manufacturing throughput deteriorates
Solution Approach 1:
The simulation model implements partial tool reservations rather than complete exclusivity for high-priority lots. Instead of reserving bottleneck tools entirely for urgent lots (excessive action), the system reserves them partially or conditionally based on simulated outcomes, allowing other lots to utilize tools when high-priority lots are not immediately due, thereby balancing delivery time improvement with maintained throughput.
Solution Approach 2:
Tool reservations for high-priority lots are dynamic rather than static, changing based on real-time simulation of delivery requirements and production capacity. The simulation model continuously evaluates whether reservations are necessary and adjusts them accordingly, ensuring that bottleneck tools are reserved only when absolutely needed for urgent deliveries, thereby minimizing impact on overall manufacturing throughput.
Data Source
AI summary
A method for processing workpieces in a process flow including a plurality of operations includes employing a fabrication simulation model of the process flow to determine an estimated completion time for a selected workpiece. The fabrication simulation model simulates the processing of the selected workpiece and other workpieces in the process flow through the plurality of operations. The priority of the selected workpiece is adjusted based on a comparison between a target completion time for the selected workpiece and the estimated completion time.