Wafer Carrier Pre-Positioning for Q-Time Transport Scheduling
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Solution Overview
Problem
Existing wafer delivery systems in semiconductor fabrication facilities face challenges with increased demand due to larger wafer sizes, leading to traffic jams and inefficiencies in cross-floor and cross-phase transportation, which affect production rates and wafer yield.
Innovation Solution
A transport system and method that includes a semiconductor apparatus, a stocker, an Over Hoist Transport (OHT) system, and a control system to prioritize and pre-position wafer carriers before load ports become available, optimizing the timing and path of wafer carrier transport to reduce waiting periods and increase production efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If wafer carriers are transported using existing delivery systems, then transportation is provided, but traffic jams occur and delivery time increases due to insufficient prioritization and late start timing
Solution Approach 1:
The control system initiates wafer carrier transportation before the load port is actually available by estimating the processed time and calculating an optimal start time. This preliminary action allows the wafer carrier to arrive ready for immediate loading, eliminating waiting time and preventing traffic jams through advance route reservation.
Solution Approach 2:
The control system continuously monitors the status of load ports, processes, and wafer carrier locations. It uses this feedback information to dynamically adjust transportation timing and routing, ensuring optimal delivery schedules and preventing congestion by coordinating multiple carriers in real-time.
2Productivity
If wafer carriers wait for load port availability, then loading can occur, but waiting periods increase and production efficiency decreases
Solution Approach 1:
The system calculates the optimal start time for wafer carrier transportation by estimating when the load port will be available and working backwards to determine when the carrier should depart. This ensures the carrier arrives precisely when needed, eliminating waiting periods while maintaining production efficiency.
Solution Approach 2:
The control system dynamically adjusts transportation schedules based on real-time conditions such as load port availability, process duration variations, and carrier positions. This dynamic coordination optimizes the timing of each carrier's journey, preventing both early arrival (causing waiting) and late arrival (reducing productivity).
3Quantity of substance
If cross-floor and cross-phase transportation volume increases to meet demand for larger wafers, then more wafers can be processed, but traffic jams occur and system efficiency decreases
Solution Approach 1:
The control system uses real-time feedback on carrier positions, load port status, and process progress to coordinate the movement of multiple wafer carriers. This feedback mechanism prevents traffic jams by adjusting routes and timing dynamically, allowing high transportation volume to be maintained without sacrificing system efficiency.
Solution Approach 2:
By initiating carrier transportation in advance based on estimated processed times and load port availability, the system prepares the transportation network ahead of demand peaks. This preliminary action smooths out traffic patterns and prevents congestion even as transportation volume increases to meet production demands.
Data Source
AI summary
A transport system is provided. The transport system includes a stocker configured to store an assigned wafer carrier and having a gate port. The transport system also includes a semiconductor apparatus configured to transmit a request signal including a processed time according to a processing wafer carrier loaded on the semiconductor apparatus. The transport system further includes a vehicle configured to transport the assigned wafer carrier from the gate port to the semiconductor apparatus and a control system configured to control the vehicle. When the control system receives the request signal, the control system controls the stocker to transport the assigned wafer carrier inside of the stocker to the gate port at a start time, which is earlier than the processed time, and the control system controls the vehicle to transport the assigned wafer carrier from the gate port to the semiconductor apparatus.