EUV Lithography Pellicle Nanotube Network 2D Material
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Solution Overview
Problem
In EUV lithography, maintaining high EUV transmittance from the light source to the wafer is challenging due to environment adsorption, and conventional pellicles fail to provide the required mechanical strength, particle blocking, and heat dissipation.
Innovation Solution
A pellicle for EUV photo masks is designed with a network membrane comprising a plurality of nanotubes and a two-dimensional material layer covering the membrane, enhancing EUV transmittance, mechanical strength, particle blocking, and heat dissipation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional pellicle is used, then the photo mask is protected from damage, dust and moisture, but the EUV transmittance is insufficient and mechanical strength is inadequate
Solution Approach 1:
The pellicle uses a composite structure combining a porous substrate layer with a nanotube network layer. The porous substrate provides mechanical strength and structural support, while the nanotube network (particularly carbon nanotubes) provides high EUV transmittance and particle blocking capability. This composite approach resolves the contradiction by allowing each material to contribute its superior properties without compromising the other.
2Reliability
If the pellicle membrane is made thinner to improve EUV transmittance, then transmittance increases, but mechanical strength and particle blocking capability decrease
Solution Approach 1:
The pellicle employs a porous substrate with controlled pore sizes and a nanotube network with specific diameter ranges (single-walled nanotubes 0.5-5nm, multi-walled nanotubes 3-20nm). The porous structure allows EUV light to pass through with high transmittance while the nanotube network acts as a physical barrier to block killer particles. The pore sizes and nanotube dimensions are carefully selected to enable simultaneous light transmission and particle filtration.
Solution Approach 2:
Different regions of the pellicle have different properties: the porous substrate provides mechanical support and initial filtration, while the nanotube network provides enhanced particle blocking and maintains EUV transmittance. The frame structure provides additional mechanical support at the boundaries. This local differentiation of properties allows the pellicle to simultaneously achieve thinness for transmittance and sufficient particle blocking capability.
3Strength
If a denser membrane structure is used to improve mechanical strength, then strength increases, but EUV transmittance decreases
Solution Approach 1:
The porous substrate maintains a controlled porosity that provides mechanical strength while allowing EUV light transmission. The nanotube network is integrated within this porous structure, with nanotubes positioned to provide reinforcement without significantly blocking light paths. The hierarchical porous-nanotube structure enables simultaneous achievement of mechanical integrity and optical transparency.
4Object-affected harmful factors
If the pellicle is designed to block all particles, then particle blocking improves, but EUV light transmission is reduced
Solution Approach 1:
The porous substrate with controlled pore sizes and the nanotube network with specific diameter ranges create a filtration system that blocks killer particles while allowing EUV light to pass. The pore sizes are larger than the nanotube diameters, creating a hierarchical structure where light can pass through both levels while particles are intercepted by the nanotube network.
Solution Approach 2:
The pellicle uses different materials and structures in different regions: the porous substrate provides initial filtration and mechanical support, while the nanotube network provides enhanced particle blocking at critical locations. The frame structure provides boundary support. This spatial differentiation allows selective blocking of particles while maintaining light transmission pathways.
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 pellicle achieves high EUV transmittance, improved mechanical strength, effective blocking of killer particles, and enhanced durability, addressing the limitations of conventional pellicles in EUV lithography.
Implementation Method 1
a nanotube layer comprising a plurality of nanotubes... effective blocking of killer particles
Implementation Method 2
a two-dimensional material layer covering the membrane, enhancing EUV transmittance, mechanical strength
Implementation Method 3
enhanced durability... heat dissipation
Data Source
AI summary
A pellicle for an EUV photo mask includes a first layer; a second layer; and a main layer disposed between the first layer and second layer and including a plurality of nanotubes. At least one of the first layer or the second layer includes a two-dimensional material in which one or more two-dimensional layers are stacked. In one or more of the foregoing and following embodiments, the first layer includes a first two-dimensional material and the second layer includes a second two-dimensional material.