Five-Layer Beryllium EUV Membrane for Uniform 13.5 nm Exposure
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Solution Overview
Problem
Existing EUV transmissive pellicle membranes suffer from significant EUV transmittance loss due to natural oxide formation and side reactions, and lack in-plane uniformity, which affects the homogeneity of semiconductor devices manufactured through EUV exposure.
Innovation Solution
A five-layer configuration of amorphous carbon/nitride/metallic beryllium/nitride/amorphous carbon layers provides high EUV transmittance and excellent in-plane uniformity by preventing natural oxide and side reaction membranes, with the nitride layers enhancing adhesion and the carbon layers offering protection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a protective layer is applied on the surface of core material to prevent natural oxide and side reaction membranes, then the EUV transmittance loss is reduced, but the protective layer itself has lower EUV transmittance than the pure core material, leading to a decrease in the overall EUV transmittance of the pellicle membrane
Solution Approach 1:
The protective layer is divided into multiple thin layers (first protective layer and second protective layer) with different materials and functions. The first protective layer (2-5 nm) provides initial protection against oxide formation, while the second protective layer (1-3 nm) provides additional protection with minimal EUV transmittance loss. This segmentation allows each layer to be optimized for its specific function while collectively achieving both protection and high transmittance.
Solution Approach 2:
Different regions of the protective layer structure have different material compositions and thicknesses tailored to their specific functions. The first protective layer uses a material optimized for oxide resistance, while the second protective layer uses a material optimized for minimal EUV absorption. This local quality differentiation allows the system to achieve both protection and high transmittance simultaneously.
2Reliability
If the thickness of protective layer is increased to improve protection, then the prevention of oxide formation is enhanced, but the EUV transmission loss increases significantly
Solution Approach 1:
Instead of using a single thick protective layer, the invention uses two thin protective layers with combined thickness optimized for both protection and transmittance. The first protective layer (2-5 nm) provides sufficient initial protection, and the second protective layer (1-3 nm) adds incremental protection while minimizing additional EUV transmittance loss. This partial action approach achieves adequate protection without excessive transmittance penalty.
Solution Approach 2:
The protective layer system uses composite materials with different properties. The first protective layer uses a material optimized for oxide resistance, while the second protective layer uses a material with even lower EUV absorption. This composite structure allows the system to achieve both protection and high transmittance that cannot be achieved with a single material.
3Device complexity
If a single-layer protective structure is used, then the device complexity is reduced, but the in-plane uniformity of EUV transmittance is insufficient
Solution Approach 1:
The protective layer is segmented into two distinct layers with different materials and thicknesses. This segmentation allows each layer to contribute differently to the overall EUV transmittance profile, improving in-plane uniformity. The first protective layer (2-5 nm) and second protective layer (1-3 nm) work together to compensate for variations and achieve more uniform transmittance across the pellicle membrane surface.
Solution Approach 2:
Different layers have different material properties and thicknesses optimized for their specific roles. The first protective layer provides oxide resistance with a thickness optimized for protection, while the second protective layer provides minimal absorption with a thinner profile. This local quality differentiation across layers improves the overall in-plane uniformity of EUV transmittance.
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 EUV transmittance of 85% or more with improved in-plane uniformity, ensuring uniform exposure and enhancing the homogeneity of semiconductor devices.
Implementation Method 1
a first protective layer that covers a side of the first nitride layer opposite to the metallic beryllium layer, wherein the first protective layer comprises amorphous carbon... to suppress the formation of these membranes
Implementation Method 2
the nitride layers enhancing adhesion
Implementation Method 3
The EUV transmissive membrane achieves EUV transmittance of 85% or more at a wavelength of 13.5 nm
Data Source
Figure 1
Figure 2A(a)~2A(f)
Figure 2B(g)~2B(j)
AI summary
Provided is an EUV transmissive membrane that exhibits high EUV transmittance and has excellent in-plane uniformity of EUV transmittance while having a protective layer on both sides thereof. The EUV transmissive membrane (10) has a five-layer configuration consisting of a metallic beryllium layer (12) having a first side and a second side; a first nitride layer (14a) including at least one selected from the group consisting of silicon nitride, beryllium nitride, boron nitride, and zirconium nitride, and a first protective layer (16a) containing amorphous carbon, which cover the first side (12a) of the metallic beryllium layer (12) in sequence; and a second nitride layer (14b) including at least one selected from the group consisting of silicon nitride, beryllium nitride, boron nitride, and zirconium nitride, and a second protective layer (16b) containing amorphous carbon, which cover the second side (12b) of the metallic beryllium layer (12) in sequence. The EUV transmissive membrane has an EUV transmittance of 85% or more at a wavelength of 13.5 nm.