Immersion Lithography Droplet Controller Gas Flow
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Solution Overview
Problem
In immersion lithography, lost liquid can cause imaging defects due to the formation of bubbles when droplets collide with the meniscus, leading to unpredictable effects and reduced throughput.
Innovation Solution
A liquid handling structure with a droplet controller and elongate gas outlet openings is used to confine and direct the immersion liquid, preventing droplets from colliding with the meniscus by allowing them to pass radially outward while blocking radial inward movement, and employing gas flows to maintain the liquid and prevent bubble formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If immersion liquid is used to improve imaging resolution, then manufacturing precision is improved, but reliability deteriorates due to bubble formation from droplet collisions
Solution Approach 1:
A gas flow is introduced as an intermediary substance between the immersion liquid and the meniscus. The gas flow creates a protective barrier that prevents liquid droplets from colliding with the meniscus, thereby eliminating bubble formation while maintaining the immersion liquid's imaging-enhancing properties
Solution Approach 2:
The invention converts the potentially harmful effect of droplet formation into a beneficial outcome by using the gas flow to redirect droplets away from the meniscus. The droplets that would otherwise cause defects are now harmlessly diverted, transforming a reliability issue into a controlled process feature
2Reliability
If liquid handling structure is added to control droplets, then reliability is improved, but device complexity increases
Solution Approach 1:
The invention uses pneumatic principles by introducing a gas flow through the liquid handling structure to control droplet movement. This pneumatic approach is more elegant and less mechanically complex than alternative solutions involving physical barriers or active droplet manipulation mechanisms
Solution Approach 2:
The liquid handling structure serves multiple functions: it confines the immersion liquid, directs the gas flow, and controls droplet movement. By combining these functions into a single integrated structure, the invention reduces overall device complexity compared to having separate components for each function
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 solution effectively reduces the risk of imaging defects and maintains or increases throughput by preventing bubble formation and ensuring stable liquid confinement during the lithographic process.
Implementation Method 1
employing gas flows to maintain the liquid and prevent bubble formation
Implementation Method 2
a plurality of elongate gas outlet openings radially outward of the space configured to direct a gas flow toward the facing surface
Implementation Method 3
supply and confine immersion liquid to a space between a projection system and a facing surface
Data Source
AI summary
A liquid handling structure for a lithographic apparatus comprises a droplet controller configured to allow a droplet of immersion liquid to be lost from the structure and to prevent the droplet from colliding with the meniscus of the confined immersion liquid. The droplet controller may comprise gas knives arranged to overlap to block an incoming droplet. There may be extraction holes lined up with gaps between gas knives to extract liquid that passes through the gap. A droplet is allowed to escape through the gaps.