Substrate Transfer Control Table for Parallel Lot Processing
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Solution Overview
Problem
Conventional substrate processing systems face challenges in predicting and controlling substrate transfer timing, leading to disturbances in transfer time, reduced throughput, and operational inefficiencies when handling multiple lots with different recipes consecutively, making it difficult to process multiple lots in parallel and requiring sequential processing.
Innovation Solution
A substrate processing system with a transfer control table that schedules substrate transfers based on a relationship between transfer timing and modules, allowing for optimized start timings and feedforward control to manage substrate movement among modules, improving operational efficiency and throughput.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the transfer position of substrate is determined every time based on transfer recipe, then the system can handle multifarious transfer recipes, but the substrate transfer timing cannot be predicted and transfer time is significantly disturbed
Solution Approach 1:
The patent applies preliminary action by pre-determining the transfer positions of all substrates in a lot before the actual transfer process begins. The transfer control table is generated in advance with all transfer positions fixed, allowing the system to handle various transfer recipes while maintaining predictable transfer timing. This is achieved by calculating and storing the complete transfer schedule before execution, rather than deciding positions dynamically during the process.
2Adaptability or versatility
If the transfer position of substrate is determined every time, then the system can accommodate different transfer recipes for each lot, but it is difficult to process multiple lots in parallel and overall processing time becomes the sum of individual lot times
Solution Approach 1:
The patent enables parallel processing of multiple lots by generating transfer control tables for multiple lots in advance and determining their start timings preliminarily. The system calculates optimal start times for each lot's transfer control table before execution, allowing multiple lots to be processed in parallel without interfering with each other, thus improving throughput while maintaining recipe flexibility.
Solution Approach 2:
The system uses feedback by monitoring the execution status of transfer control tables and adjusting the start timing of subsequent lots based on the completion status of previous lots. This allows dynamic coordination of multiple lots while maintaining the overall parallel processing capability and preventing substrate passing issues between lots.
3Loss of information
If conventional control method is used with memory storing present positional information, then the system can track substrate position, but feedforward control predicting future transfer timing is difficult
Solution Approach 1:
The patent eliminates the need for continuous position tracking during transfer by pre-determining all transfer positions in the transfer control table before the process begins. The system generates the complete transfer schedule in advance, which includes all future transfer timings and positions, enabling feedforward control where the entire transfer sequence is executed according to the pre-calculated plan without real-time position monitoring.
Data Source
AI summary
A transfer schedule SA and a transfer schedule SB for an A lot and a B lot different from each other are generated on a transfer control table, the succeeding transfer schedule SB is moved ahead in the direction of a time axis within a range over which it does not interfere with the transfer schedule SA for the preceding A lot to make the start timing for the succeeding transfer schedule SB become earlier than the end timing for the transfer schedule for the preceding A lot, so that the transfer schedule SA and the transfer schedule SB are executed in parallel, thereby improving the throughput a wafer transfer process.