Multi-Stage Lithography Stage Positioning via Segmented Coil Control
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Solution Overview
Problem
Conventional multi-stage lithographic systems cannot allow two stages to approach each other closely due to overlapping coil interactions, limiting operational capabilities.
Innovation Solution
A multi-stage system with a stator and two moveable stages, each with a magnetic field, uses a sensor system and control unit to selectively activate electric coils for precise positioning, excluding coils that would interfere with both stages to enable closer approach.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If all electric coils are activated to position the first stage, then positioning accuracy is improved, but coil overlap with the second stage occurs preventing close proximity
Solution Approach 1:
The control system segments the electric coils into multiple groups based on their spatial locations. When positioning the first stage, only coils in the first group (spatially close to the first stage) are activated, while coils in the second group (spatially close to the second stage) remain inactive. This segmentation allows stages to approach closely without coil interference while maintaining positioning accuracy through selective coil activation.
Solution Approach 2:
The system applies local quality by activating only the specific subset of coils that are locally relevant to the stage being positioned. Instead of uniform activation of all coils, the control system identifies and activates only those coils in the first group that are spatially proximate to the first stage, creating a localized magnetic field interaction that avoids interference with the second stage.
2Adaptability or versatility
If a subset of coils is activated to avoid overlap, then stage proximity is improved, but positioning accuracy may deteriorate
Solution Approach 1:
The coil array is segmented into distinct groups based on spatial proximity to each stage. The control system selectively activates coils in the first group for first stage positioning, ensuring sufficient coils are engaged to maintain accuracy while preventing overlap with the second stage. This segmentation strategy balances proximity capability with positioning precision.
Solution Approach 2:
The control system performs preliminary identification of which coils belong to the first group versus the second group based on their spatial relationships to the stages. This preliminary classification enables the system to pre-determine the optimal subset of coils to activate, ensuring both accurate positioning and prevention of coil overlap before the positioning operation begins.
3Device complexity
If the same coils are used to position both stages, then device complexity is reduced, but independent positioning capability is lost
Solution Approach 1:
The coil system is segmented into at least two distinct groups: a first group of coils spatially associated with the first stage and a second group spatially associated with the second stage. This segmentation enables independent positioning control of each stage using its dedicated coil group, providing full independent positioning capability while utilizing a single shared coil array structure, thus balancing complexity reduction with operational independence.
Solution Approach 2:
The same physical coil array serves multiple functions by being selectively activated for different stages. The first group of coils can position the first stage, while the second group positions the second stage, allowing a single coil system to provide independent positioning capability for multiple stages without requiring separate coil arrays for each stage.
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
Enables independent and precise positioning of two stages relative to the stator, allowing them to approach each other more closely, thereby expanding operational possibilities in lithographic processes.
Implementation Method 1
the electric coils being configured to interact with the magnetic fields generated by the system of magnets of the first and second stage in order to generate forces on the first and second stage to position them relative to the stator
Data Source
AI summary
A multi-stage system includes a stator including a plurality of electric coils; a first stage including a first magnet assembly, the first stage moveable relative to the stator; a second stage including a second magnet assembly, the second stage moveable relative to the stator; a controller configured to position the first and the second stage relative to the stator by activating, respectively, a first subset of the plurality of electric coils to interact with the first magnet assembly and a second subset of the plurality of electric coils to interact with the second magnet assembly, the controller adapted to prevent at least one electric coil, to be simultaneously shared by the first and the second subset to position the first and the second stage on the stator, from activating.