Buffer Chamber and Flexible Wall for Lithography Fluid Extraction
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Solution Overview
Problem
The two-phase extraction system in lithographic apparatuses experiences unstable flow characteristics, leading to undesirable mechanical effects such as vibrations on the substrate and substrate table, which result in imaging errors.
Innovation Solution
A fluid extraction system is implemented with a buffer chamber and a separation tank, where the extraction channel allows two-phase fluid flow and the buffer chamber is configured to absorb pressure fluctuations, and a flexible boundary portion is used to deform in response to pressure changes, reducing pressure fluctuations in the fluid extraction system.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a two-phase extraction system is used to remove fluid in lithographic apparatus, then fluid removal efficiency is improved, but flow stability deteriorates causing vibrations and imaging errors
Solution Approach 1:
A buffer chamber is introduced as an intermediary component between the extraction channel and the pump. This buffer chamber absorbs pressure fluctuations and stabilizes the two-phase fluid flow, preventing vibrations while maintaining efficient fluid removal. The buffer chamber acts as a mediator that decouples the unstable extraction process from the stable pump operation.
Solution Approach 2:
The buffer chamber provides beforehand cushioning by absorbing pressure fluctuations before they can propagate through the system and cause vibrations. By pre-stabilizing the flow in the buffer chamber, the system prevents harmful vibrations from occurring downstream, thereby maintaining imaging precision while preserving high fluid removal efficiency.
2Manufacturing precision
If immersion liquid is used to fill space between projection system and substrate, then imaging resolution is improved, but pressure fluctuations increase causing vibrations
Solution Approach 1:
The buffer chamber serves as an intermediary that isolates the immersion liquid from pressure fluctuations. By positioning the buffer chamber in the fluid extraction path, it absorbs pressure variations before they can affect the immersion liquid between the projection system and substrate, thereby maintaining both high imaging resolution and mechanical stability.
Solution Approach 2:
The system changes the physical parameters of the fluid extraction by introducing a buffer volume that dampens pressure fluctuations. This parameter change in the extraction system allows the immersion liquid to maintain stable pressure conditions, preserving imaging resolution while eliminating harmful vibrations.
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 reduces pressure fluctuations and vibrations, thereby minimizing imaging errors and improving the stability of the substrate and substrate table during the lithographic process.
Implementation Method 1
a buffer chamber containing a volume of gas, the buffer chamber being fluidly connected to the extraction channel
Implementation Method 2
the fluid extraction system being configured such that liquid is substantially prevented from entering the buffer chamber
Implementation Method 3
At least a portion of a wall of the extraction channel and/or at least a portion of a wall of the separation tank comprises a flexible boundary portion configured to deform in response to a change in the pressure differential across it
Data Source
AI summary
An immersion lithographic apparatus typically includes a fluid handling system. The fluid handling system generally has a two-phase fluid extraction system configured to remove a mixture of gas and liquid from a given location. Because the extraction fluid comprises two phases, the pressure in the extraction system can vary. This pressure variation can be passed through the immersion liquid and cause inaccuracy in the exposure. To reduce the pressure fluctuation in the extraction system, a buffer chamber may be used. This buffer chamber may be connected to the fluid extraction system in order to provide a volume of gas which reduces pressure fluctuation. Alternatively or additionally, a flexible wall may be provided somewhere in the fluid extraction system. The flexible wall may change shape in response to a pressure change in the fluid extraction system. By changing shape, the flexible wall can help to reduce, or eliminate, the pressure fluctuation.