Beryllium-Core EUV Pellicle With Nitride Oxide Protection
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Solution Overview
Problem
Existing EUV transmissive pellicles suffer from significant EUV transmittance loss due to natural oxide formation and protective layers, which degrade their performance.
Innovation Solution
A three-layer configuration of metallic beryllium and nitride layers, with amorphous carbon layers on both sides, is used to prevent oxide formation and maintain high EUV transmittance, followed by removal of the amorphous carbon layers using hydrogen or oxygen plasma to enhance transmittance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a protective layer is applied on the surface of the core material to prevent oxide formation, then the reliability of the pellicle membrane is improved, but the EUV transmittance deteriorates due to the lower transmittance of the protective layer
Solution Approach 1:
The patent applies a protective layer (such as silicon nitride or boron nitride) on the core material surface before oxide formation occurs. This preliminary protective action prevents oxidation during storage and handling while the layer thickness is carefully controlled (1-10 nm) to minimize EUV transmittance loss. The protective layer serves its function in advance, and then its impact is minimized for the actual EUV application.
Solution Approach 2:
The patent changes the parameters of the protective layer, specifically using ultra-thin thickness (1-10 nm range) and selecting materials with appropriate EUV transmittance characteristics. By adjusting the thickness parameter to be as small as possible while still providing oxidation protection, and selecting materials like silicon nitride or boron nitride that have relatively high EUV transmittance, the contradiction between protection and transmittance is resolved.
2Reliability
If a thick protective layer is used to ensure sufficient protection, then the reliability is improved, but the EUV transmittance loss increases significantly
Solution Approach 1:
The patent applies just enough protective layer thickness to achieve sufficient oxidation protection without excessive thickness that would harm transmittance. The thickness is optimized to the minimum required level (1-10 nm), which is partially sufficient for protection during handling but minimal enough to preserve EUV transmittance. This avoids the excessive action of applying thick protective layers.
Solution Approach 2:
The patent changes the thickness parameter of the protective layer to an ultra-thin range (1-10 nm), transforming it from a conventional thick protective layer to an atomic-scale thin film. This parameter change allows the layer to provide protection at the molecular level while being transparent enough to EUV light to minimize transmittance loss.
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 EUV transmissive membrane achieves an EUV transmittance of 88% or more at 13.5 nm, maintaining high performance by preventing transmittance loss and ensuring structural integrity.
Implementation Method 1
the core material having high EUV transmittance used for the pellicle membrane as described above forms a natural oxide membrane of several nm on the surface thereof in air, and the oxide membrane absorbs EUV, resulting in a decrease in EUV transmittance of the pellicle membrane
Implementation Method 2
followed by removal of the amorphous carbon layers using hydrogen or oxygen plasma to enhance transmittance
Data Source
Figure 1
Figure 2A(a)~2A(f)
Figure 2B(g)~2B(k)
AI summary
Provided is an EUV transmissive membrane that exhibits high EUV transmittance. The EUV transmissive membrane (10) has a three-layer configuration composed of a metallic beryllium layer (12) having a first side and a second side, a first nitride layer (14a) that covers the first side (12a) of the beryllium layer (12), wherein the first nitride layer includes at least one selected from the group consisting of silicon nitride, beryllium nitride, boron nitride, and zirconium nitride, and a second nitride layer (14b) that covers the second side (12b) of the beryllium layer (12), wherein the second nitride layer includes at least one selected from the group consisting of silicon nitride, beryllium nitride, boron nitride, and zirconium nitride. The EUV transmissive membrane (10) has an EUV transmittance of 88% or more at a wavelength of 13.5 nm.