Immersion Lithography Substrate Table Pressure Dampers
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In immersion lithography, the thermal conditioning of substrates is challenging due to pressure variations in the conditioning fluid, which can cause substrate deformation and impact overlay and focus stability, especially during acceleration of the substrate table.
Innovation Solution
A lithographic apparatus with a conditioning system that includes pressure dampers to isolate the conditioning fluid from external pressure variations, using a combination of expansion tanks and active pressure control to maintain stable fluid pressure, thereby reducing deformation and maintaining substrate stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the substrate table is accelerated during scanning exposure, then productivity is improved, but pressure variations in the conditioning fluid cause substrate deformation and worsen manufacturing precision
Solution Approach 1:
A gas cushion is introduced as an intermediary between the conditioning fluid and the substrate table. The gas cushion absorbs and isolates pressure variations from the conditioning fluid, preventing them from being transmitted to the substrate table during acceleration, thus maintaining substrate stability while enabling high-speed scanning
Solution Approach 2:
The patent utilizes pneumatic isolation by introducing a gas layer between the liquid conditioning fluid and the substrate table. This gas cushion acts as a pressure isolator, allowing the substrate table to be accelerated without transmitting fluid pressure variations to the substrate, thereby resolving the contradiction between speed and precision
2Measurement precision
If a large body of liquid is used for immersion, then imaging resolution is improved, but additional powerful motors are required and turbulence causes harmful effects
Solution Approach 1:
The immersion liquid is segmented into two distinct regions: a large body of liquid above the substrate table that provides imaging resolution, and a restricted liquid-free zone between the projection system and substrate table that eliminates turbulence. This segmentation allows the benefits of immersion lithography without the harmful effects of liquid acceleration
Solution Approach 2:
The liquid is extracted from the critical scanning zone between the projection system and substrate table, while maintaining a large body of liquid above the substrate table for imaging purposes. This removal of liquid from the acceleration zone eliminates turbulence and the need for powerful motors, while preserving imaging resolution
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
The pressure dampers effectively reduce pressure fluctuations, minimizing substrate deformation and maintaining stable overlay and focus, even during substrate table acceleration, thus enhancing the precision of the lithographic process.
Implementation Method 1
The conditioning system comprises a pressure damper in fluid communication with the conditioning system and arranged to dampen a pressure variation in the conditioning system
Implementation Method 2
The pressure damper comprises an expansion tank having a first compartment and a second compartment, the first compartment being in fluid communication with the conditioning system and the second compartment containing a gas
Data Source
AI summary
A lithographic apparatus is disclosed that is arranged to project a pattern from a patterning device onto a substrate, the lithographic apparatus has a substrate table configured to hold a substrate. The substrate table includes a conditioning system configured to hold a conditioning fluid and to condition the substrate table. The conditioning system includes a pressure damper that is in fluid communication with the conditioning system and is arranged to dampen a pressure variation in the conditioning system.