EUV Pellicle Composite Structure for Transmissivity and Strength
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Solution Overview
Problem
Lithographic apparatuses, particularly those using EUV radiation, face challenges with pellicle transmissivity and stability due to absorption and contamination issues, leading to reduced performance and increased operating temperatures, while spectral purity filters suffer from delamination and degradation under high heat loads and hydrogen exposure.
Innovation Solution
An optical element with a self-terminating growth top layer supported by an anchor layer, combined with a substrate and wetting layer, provides resistance to etching and deposition, maintaining stability and transmissivity, and a non-volatile sacrificial material protects pellicle membranes from hydrogen-induced erosion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the pellicle is made thinner to increase EUV transmissivity, then transmissivity is improved, but mechanical strength and reliability deteriorate
Solution Approach 1:
The pellicle employs a composite structure consisting of a silicon carbide substrate with deposited layers of ruthenium and zirconium oxide. This composite material approach allows the thin pellicle (50-200 nm) to maintain high EUV transmissivity while the combination of materials provides the necessary mechanical strength and chemical stability to withstand the harsh lithography environment.
Solution Approach 2:
The invention utilizes an extremely thin pellicle membrane (50-200 nm thickness) made from silicon carbide, which is supported by a thin frame. This thin film structure minimizes EUV radiation absorption while maintaining structural integrity through the inherent strength of silicon carbide and the supporting frame architecture.
2Temperature
If the pellicle is made thinner to reduce operating temperature, then temperature is reduced, but mechanical strength deteriorates
Solution Approach 1:
The silicon carbide substrate combined with ruthenium and zirconium oxide coating layers creates a composite structure that has both low thermal mass (reducing operating temperature) and high mechanical strength. The thin profile (50-200 nm) ensures low heat absorption while the material composition maintains structural integrity.
3Object-affected harmful factors
If spectral purity filters are used to block out-of-band radiation, then spectral purity is improved, but delamination and degradation occur under high heat loads
Solution Approach 1:
The invention changes the material parameters by using silicon carbide as the substrate material instead of traditional filter materials. Silicon carbide has high thermal conductivity and high melting point, allowing the pellicle to withstand high heat loads from out-of-band radiation blocking without delamination or degradation.
Solution Approach 2:
The combination of silicon carbide substrate with ruthenium and zirconium oxide layers creates a composite structure that provides both spectral filtering capability and thermal stability. The zirconium oxide layer specifically provides thermal barrier properties while the ruthenium layer provides chemical stability in the hydrogen-rich environment.
4Object-affected harmful factors
If conventional pellicles are used in EUV lithography, then particle protection is provided, but contamination and absorption reduce performance over time
Solution Approach 1:
The invention changes the chemical composition parameters by using silicon carbide instead of traditional polymer or silicon dioxide materials. Silicon carbide has superior chemical inertness and resistance to EUV-induced contamination, maintaining performance stability over time while still providing particle protection.
Solution Approach 2:
The pellicle is designed as a replaceable component with a simple structure that can be quickly exchanged. The thin silicon carbide membrane provides effective particle protection, and when contamination does occur, the entire pellicle can be replaced without affecting other system components.
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 ensures stable performance and extended lifespan of optical elements and pellicle membranes by preventing etching and deposition, maintaining high transmissivity and resistance to plasma environments, thus enhancing the operational efficiency and uptime of lithographic apparatuses.
Implementation Method 1
a top layer having self-terminating growth in an operating lithographic apparatus
Implementation Method 2
a wetting layer provided between the substrate and the anchor layer
Implementation Method 3
a non-volatile sacrificial material provided in an area of the membrane outside the light path of an operating lithographic apparatus
Data Source
AI summary
An optical element for a lithographic apparatus, the optical element including an anchor layer selected to support a top layer having self-terminating growth in an operating lithographic apparatus or plasma containing environment. Also described is a method of manufacturing an optical element, the method including depositing a top layer on anchor layer via exposure to plasma, preferably electromagnetically induced plasma. Lithographic apparatuses including such optical elements are also described.