Lithographic Apparatus Utility Substrate Scheduling
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Solution Overview
Problem
In lithographic systems, the scheduling of utility substrates like closing substrates is inadequate due to delays in transferring them from the substrate track to the substrate support, causing gaps in the substrate flow and affecting product quality and throughput.
Innovation Solution
A utility substrate scheduling unit and a substrate handler are integrated to detect gaps in the substrate flow and schedule the loading of utility substrates, such as closing substrates, directly from a storage device to the substrate support, bypassing existing substrates and minimizing delays.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If utility substrates are transferred from the substrate track to the substrate support through the normal substrate flow path, then the substrate handler can process substrates sequentially, but this causes delays and gaps in the substrate flow
Solution Approach 1:
The patent segments the substrate handling process into two independent paths: one for process substrates through the substrate track, and another for utility substrates directly from the utility substrate storage device to the substrate support. This segmentation allows utility substrate loading to occur independently without blocking the main substrate flow, resolving the contradiction between ease of operation and productivity.
Solution Approach 2:
The utility substrate storage device acts as an intermediary component that holds utility substrates separately from the main substrate track. This intermediary allows the substrate handler to retrieve utility substrates directly without interrupting the normal substrate flow through the substrate track, thereby maintaining continuous substrate flow while still enabling utility substrate processing.
2Productivity
If closing substrates are loaded late to fill gaps in substrate flow, then existing substrates can be processed, but this causes delays in closing the immersion space and increasing post-exposure bake times
Solution Approach 1:
The patent implements preliminary action by pre-loading closing substrates into the utility substrate storage device before they are actually needed. The substrate handler is configured to retrieve and install closing substrates proactively when gaps are detected, rather than reactively after the gap causes problems. This preliminary preparation ensures that closing substrates are ready immediately, minimizing delays in closing the immersion space and reducing post-exposure bake times.
Solution Approach 2:
The system incorporates feedback mechanisms where the substrate handler monitors the substrate flow and detects gaps in real-time. When a gap is detected, the feedback signal triggers the substrate handler to retrieve a closing substrate from the utility substrate storage device and install it immediately. This closed-loop feedback system ensures timely gap filling without requiring manual intervention or causing unnecessary delays.
3Device complexity
If the substrate handler transfers utility substrates through the substrate track, then existing infrastructure is used, but this creates gaps in substrate flow and affects throughput
Solution Approach 1:
The patent segments the substrate handling infrastructure into two distinct pathways: the substrate track for process substrates and a direct transfer path from the utility substrate storage device for utility substrates. This segmentation allows the system to utilize existing infrastructure for normal operations while introducing a dedicated efficient path for utility substrate handling, thereby maintaining high substrate throughput without significantly increasing overall system complexity.
Solution Approach 2:
The utility substrate storage device and substrate handler are designed with multi-functionality to serve both the utility substrate loading process and the main substrate flow process. The substrate handler can selectively transfer substrates from either the substrate track or the utility substrate storage device to the substrate support, making the system more versatile and efficient. This multi-functional design improves productivity by avoiding the need for separate dedicated infrastructure while maintaining optimized flow paths.
Data Source
AI summary
A lithographic apparatus is disclosed that includes a utility substrate storage configured to hold a utility substrate, and a utility substrate scheduling unit configured to schedule the loading of a utility substrate in a flow of substrates in the lithographic apparatus.