Capillary Liquid Substrate Clamp Sealing Rim Design
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Solution Overview
Problem
Existing substrate clamping methods in vacuum environments face challenges such as evaporation of liquid clamping layers, vapor leakage, and contamination issues, which affect the stability and longevity of the clamping force in lithography processes.
Innovation Solution
A substrate support structure with a capillary layer of liquid, featuring a sealing structure, cantilever arrangement, and capillary layer localization, which includes portions with different capillary potentials to manage evaporation, vapor leakage, and substrate peeling, and incorporates a liquid reservoir and moat for vapor management.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a liquid clamping layer is used to clamp a substrate on a substrate support structure surface, then the clamping force is enhanced and thermal contact is improved, but evaporation of the liquid layer occurs over time which deteriorates the clamping force and limits the useful lifetime of the clamp
Solution Approach 1:
The patent extracts the harmful evaporated vapor from the system by introducing a vacuum pump that actively removes vapor from the chamber. This allows the liquid clamping layer to maintain its clamping force over extended periods without degradation from evaporation, directly resolving the contradiction between initial clamping strength and duration of action.
Solution Approach 2:
The patent changes the environmental parameters by maintaining a controlled atmosphere (vacuum or inert gas) in the chamber. This parameter change prevents evaporation of the liquid clamping layer, allowing the clamp to maintain its strength throughout the intended operational lifetime.
2Strength
If a liquid clamping layer is used to clamp a substrate, then adhesion creates a circumferentially extending liquid surface that maintains shape under force, but leakage of vapor from the liquid layer contaminates the vacuum environment and is detrimental to lithography processes
Solution Approach 1:
The vacuum pump extracts harmful vapor leakage from the chamber before it can contaminate the vacuum environment. This extraction mechanism allows the liquid clamping layer to provide strong adhesion-based clamping force while preventing vapor from reaching the lithography process area.
Solution Approach 2:
The patent introduces a vacuum pump as an intermediary system between the liquid clamping layer and the vacuum environment. This intermediary actively manages vapor leakage, allowing the clamping layer to function effectively without harming the vacuum integrity required for lithography.
3Temperature
If a liquid clamping layer is used to clamp a substrate, then thermal contact between substrate and support structure is enhanced, but condensation of vapor from the clamping liquid reduces the lifetime of the clamp
Solution Approach 1:
The vacuum pump extracts water vapor before it can condense on the substrate or support structure. This prevents condensation-related degradation of the clamping system while preserving the beneficial thermal contact provided by the liquid layer.
Solution Approach 2:
The patent controls the thermal and pressure parameters of the system by maintaining vacuum conditions and potentially controlling chamber temperature. This prevents vapor condensation that would otherwise reduce clamp lifetime, while allowing the liquid layer to provide enhanced thermal contact during operation.
4Productivity
If the substrate is positioned close to the outer edge of the substrate support structure surface for optimal support, then support efficiency is improved, but the liquid clamping layer cannot be properly sealed at the periphery allowing vapor leakage
Solution Approach 1:
The vacuum pump extracts vapor from the entire chamber including areas near the substrate periphery. This allows the substrate to be positioned for optimal support efficiency without compromising the sealing of the liquid clamping layer, as the pump removes vapor that would otherwise leak at the periphery.
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 solution enhances the stability and longevity of the clamping force by reducing evaporation, minimizing vapor leakage, and maintaining a consistent capillary flow, thereby extending the clamp's useful life and ensuring reliable substrate holding during lithography processes.
Implementation Method 1
using a liquid layer arranged to induce a capillary force such that the substrate is clamped on a surface of a substrate support structure
Implementation Method 2
Adhesion of the liquid to the surfaces of the substrate on the one hand and the substrate support structure on the other hand creates a circumferentially extending liquid surface
Implementation Method 3
The liquid layer may further serve the purpose of enhancing the thermal contact between the substrate and the substrate support structure surface to enable the substrate to withstand higher heat loads
Implementation Method 4
Evaporation of the clamping liquid layer results in deterioration of the clamping force over time, which limits the useful lifetime of the clamp
Implementation Method 5
Condensation of vapor from the clamping liquid may also pose a problem, reducing the lifetime of the clamp
Data Source
AI summary
A substrate support structure (13) for clamping a substrate (12) on a surface (16) by means of a capillary layer of a liquid (11). The surface has an outer edge (28) and includes one or more substrate supporting elements (17) for receiving the substrate to be clamped, wherein the one or more substrate supporting elements are arranged to provide support for the substrate at a plurality of support locations. The substrate support structure further includes a sealing structure (21) circumscribing the surface and having a top surface or edge (22, 24, 26) forming a sealing rim. A distance (c) between the outer edge of the surface and an outermost of the support locations is greater than a distance (d) between the outer edge and the sealing rim.