Lithography Substrate Holder Foreign Substance Detection
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Solution Overview
Problem
In semiconductor exposure processes, foreign substances on the wafer chuck can cause local defocusing and resolution failures, leading to reduced productivity and the need for frequent apparatus shutdowns for cleaning, as existing methods are inadequate in removing highly adhesive residues and require external cleaning equipment.
Innovation Solution
A lithography apparatus with a substrate holder, a cleaning unit, and a controller that detects foreign substances and decides whether to perform a cleaning operation before proceeding with pattern formation, allowing subsequent operations to continue without cleaning if the substance is detected at the same position repeatedly, thereby improving focus tracking and minimizing downtime.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If foreign substances are detected and cleaning operations are performed, then image quality and resolution are improved, but productivity decreases due to frequent apparatus shutdowns
Solution Approach 1:
The system performs preliminary detection of foreign substances on the wafer chuck before exposure processing using a detector. When a foreign substance is detected, the system executes a cleaning operation in advance before the actual exposure process, preventing image quality degradation without requiring apparatus shutdown during production. This preliminary action allows the system to maintain both high image quality and continuous productivity.
2Reliability
If cleaning operations are performed frequently to remove foreign substances, then resolution failures are prevented, but cleaning equipment wear increases
Solution Approach 1:
The system employs a detector to continuously monitor the wafer chuck surface for foreign substances and provides feedback to the control unit. The control unit intelligently determines when cleaning is necessary based on actual detection results, executing cleaning operations only when foreign substances are detected. This feedback-based approach prevents unnecessary cleaning operations, reducing wear on cleaning equipment while maintaining resolution quality by cleaning only when needed.
3Reliability
If external cleaning apparatus are used to remove foreign substances, then cleaning effectiveness is improved, but apparatus downtime increases
Solution Approach 1:
The system merges the cleaning function with the lithography apparatus by integrating a cleaning unit directly into the apparatus structure. The cleaning unit can be operated in conjunction with the detector to perform cleaning operations without requiring substrate holder detachment or external cleaning equipment. This integration eliminates the need for apparatus shutdown and external cleaning apparatus, maintaining cleaning effectiveness while preventing productivity loss from extended downtime.
Data Source
AI summary
A lithography apparatus includes a cleaning unit configured to perform cleaning of a substrate holder, a detector configured to detect a foreign substance by observing a substrate held by the substrate holder, and a controller configured to control execution of a pattern forming operation on the substrate and a cleaning operation. The controller operates such that, if a foreign substance is detected out of a predetermined area including a position at which a foreign substance was previously detected after a predetermined number of executions of the cleaning operation, a next pattern forming operation is performed after executing the cleaning operation. Otherwise, a next pattern forming operation is performed without executing the cleaning operation.