Uncoupled Masking Structures for High-Speed Lithography
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Solution Overview
Problem
Conventional masking devices in lithographic projection apparatuses face challenges in achieving high scanning speeds due to the mass of coupled X-Y blades, which limits acceleration and deceleration, and causes vibrations that disturb other components.
Innovation Solution
The masking device comprises mechanically uncoupled first and second masking structures, with the first structure being thinner and cooled to reduce mass and size, allowing higher accelerations and scanning speeds while preventing vibrations from transferring between structures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If coupled X-Y blades are used in conventional masking devices, then the masking function is provided, but the mass of the coupled blades limits acceleration and deceleration, preventing high scanning speeds
Solution Approach 1:
The masking device is divided into two separate masking structures (first and second masking structures) that are mechanically uncoupled from each other. This segmentation allows each structure to be moved independently by separate driving mechanisms, reducing the effective mass that each driver must accelerate and decelerate, thereby enabling higher scanning speeds.
Solution Approach 2:
The patent replaces the conventional mechanically coupled blade system with a thermally actuated system. The first masking structure is cooled to reduce its mass and size, and thermally actuated elements are used to move the masking structures, substituting traditional mechanical coupling with thermal actuation mechanisms that enable faster acceleration and deceleration.
2Reliability
If coupled X-Y blades are used in conventional masking devices, then the masking function is provided, but vibrations are generated that disturb other components
Solution Approach 1:
By mechanically uncoupling the first and second masking structures, vibrations generated by one structure do not transfer to the other structure or to other components of the lithographic apparatus. This isolation eliminates the harmful vibration effect while maintaining the masking function through the coordinated operation of the separate structures.
Solution Approach 2:
The patent introduces separate driving mechanisms for each masking structure, acting as intermediaries that independently control the position and movement of each structure. This intermediary control system allows precise positioning while isolating vibration sources, preventing disturbance to other components.
3Strength
If thicker masking structures are used, then structural strength is maintained, but mass increases reducing acceleration capability
Solution Approach 1:
The patent changes the thermal state parameter of the first masking structure by cooling it. This temperature reduction causes thermal contraction, decreasing the dimensions and mass of the masking structure. The cooled structure achieves the necessary strength at reduced mass, enabling higher acceleration capability while maintaining structural integrity.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This configuration enables higher scanning speeds and accelerations without disturbing other components, improving the masking function and reducing the required driving forces, allowing for sharper edges and more efficient masking during both static and scanning exposures.
Implementation Method 1
the first masking structure being thinner and cooled to reduce mass and size
Data Source
AI summary
A lithographic projection apparatus having a masking device for obscuring part of at least one of a patterning device used for patterning a projection beam before imaging the patterned beam onto a substrate. The masking device includes a first masking structure to obscure said part of said patterning device in a first direction and a second masking structure to obscure said part in a second different direction, wherein said first and second masking structure are disposed in the vicinity of said focal plane in a mechanically uncoupled arrangement with respect to each other.