Wafer Table Inspection for Atmospheric Burl and Cleaning Verification
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Solution Overview
Problem
Current lithography systems face significant downtime and inefficiencies in inspecting and cleaning wafer tables due to the need for vacuum cycling and multiple cleaning cycles, leading to inaccurate performance verification and reduced productivity.
Innovation Solution
A wafer table inspection tool that can be positioned over the wafer table within the lithography system, allowing for direct inspection and evaluation of surface burls and cleaning performance without vacuum cycling, using image sensors and machine learning for efficient cleaning operation planning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If vacuum cycling is performed for inspection, then measurement accuracy is improved, but loss of time increases
Solution Approach 1:
The inspection function is extracted from the vacuum environment and performed in atmospheric conditions using a separate inspection tool that accesses the wafer table through an opening in the bottom module, eliminating the need to cycle the vacuum system for inspection purposes
Solution Approach 2:
An inspection tool serves as an intermediary device that can observe and measure the wafer table surface through an opening without requiring the entire system to be in vacuum mode, enabling atmospheric inspection while maintaining measurement capability
2Reliability
If multiple cleaning cycles are performed, then cleaning quality is improved, but productivity decreases
Solution Approach 1:
The inspection tool provides immediate feedback on wafer table surface condition and cleaning quality, allowing for single-cycle cleaning operations to be verified and approved without requiring multiple redundant cleaning cycles, thereby improving productivity while maintaining cleaning quality
Solution Approach 2:
Inspection is performed immediately after cleaning in atmospheric conditions to verify cleaning quality before the wafer table is reinstalled, allowing for immediate determination of whether cleaning was sufficient and eliminating the need for multiple cleaning cycles
3Reliability
If vacuum cycling is performed, then inspection reliability is improved, but device complexity increases
Solution Approach 1:
The inspection function is extracted from the vacuum system operations, allowing inspection to be performed independently in atmospheric conditions through an opening in the bottom module, reducing the complexity of coordinating vacuum cycling with inspection procedures
Solution Approach 2:
The inspection tool is integrated into the bottom module structure and can access the wafer table directly through an opening, enabling the inspection system to serve itself without requiring the main lithography system to undergo complex vacuum state changes
Data Source
AI summary
A wafer table inspection tool described herein is capable of being positioned over a wafer table while the wafer table is positioned in a bottom module of an exposure tool of a lithography system. The wafer table inspection tool is capable of quickly evaluating the condition of surface burls on the wafer table and evaluating cleaning performance of a cleaning operation in which the surface burls are cleaned.