Rare Earth Outer Layer for Lithographic Sensor Hydrophobicity
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Lithographic apparatus sensor marks with hydrophobic coatings suffer degradation due to exposure to deep ultraviolet radiation, leading to reduced hydrophobicity and imaging errors.
Innovation Solution
A substrate with an outer layer comprising a rare earth element, which maintains hydrophobicity and resistance to degradation, is used in the lithographic apparatus, with the rare earth element being incorporated through methods such as sputtering, PVD, CVD, ALD, or plasma-induced polymerization, ensuring a receding contact angle of at least 75° with water.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If hydrophobic coating is applied to sensor mark, then liquid loss is reduced and heat load is reduced, but the coating degrades due to deep ultraviolet radiation exposure
Solution Approach 1:
The patent applies a composite coating structure consisting of a lower hydrophobic layer (e.g., fluorocarbon-based) providing water repellency and an upper protective layer (e.g., silicon oxide, silicon nitride, or diamond-like carbon) resistant to deep ultraviolet radiation. This multi-layer composite structure combines the benefits of hydrophobicity with radiation resistance, preventing both liquid loss and coating degradation.
Solution Approach 2:
The patent modifies the chemical composition and physical properties of the outer layer by incorporating specific materials with known radiation resistance characteristics. By changing the material parameters (composition, thickness, cross-linking density) of the upper layer, the coating system achieves simultaneous hydrophobicity and stability under deep ultraviolet exposure.
2Loss of energy
If upper hydrophobic layer is applied to sensor mark, then liquid loss is reduced, but the layer degrades due to exposure to deep ultra violet radiation
Solution Approach 1:
The patent employs a composite coating where the upper layer is specifically designed to be resistant to deep ultraviolet radiation while the lower layer provides hydrophobicity. This composite structure prevents the degradation issues that would occur with a single hydrophobic layer exposed directly to radiation.
Solution Approach 2:
The upper protective layer acts as an intermediary between the immersion liquid and the deep ultraviolet radiation, shielding the lower hydrophobic layer from radiation damage while allowing the hydrophobic properties to function. This mediator layer absorbs or blocks the harmful radiation before it can degrade the hydrophobic coating.
3Ease of operation
If coating is applied to substrate, then desired property (e.g. hydrophobic) is achieved, but coating degrades generating particles that introduce imaging errors
Solution Approach 1:
The patent uses a composite coating structure where the upper protective layer prevents degradation of the lower functional layer. This composite structure eliminates particle generation from coating degradation, ensuring no imaging errors occur while maintaining the desired hydrophobic properties.
Solution Approach 2:
The upper protective layer serves as a pre-established protective barrier that prevents future degradation of the hydrophobic coating. By providing this protective cushioning in advance, the system prevents particle generation and imaging errors before they can occur during operation.
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 rare earth element-based outer layer provides enhanced resistance to degradation and maintains hydrophobicity, preventing imaging errors and ensuring consistent performance under exposure to deep ultraviolet radiation.
Implementation Method 1
the outer layer has a composition comprising a rare earth element... water makes a receding contact angle of at least 75° with the outer layer
Implementation Method 2
the rare earth element being incorporated through methods such as sputtering, PVD, CVD, ALD, or plasma-induced polymerization
Implementation Method 3
the rare earth element being incorporated through methods such as sputtering, PVD, CVD, ALD, or plasma-induced polymerization
Implementation Method 4
the rare earth element being incorporated through methods such as sputtering, PVD, CVD, ALD, or plasma-induced polymerization
Data Source
AI summary
An object, such as a sensor for an immersion lithographic apparatus, has an outer layer which comes in contact with immersion liquid and wherein the outer layer has a composition including a rare earth element. There is also provided an immersion lithographic apparatus having such an object and a method for manufacturing such an object.