EUV Pellicle Layer Structure for Transmittance and Mask Protection
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Solution Overview
Problem
Current pellicle materials for extreme ultraviolet lithography do not meet the requirements of high transmittance, thermal stability, mechanical stability, and chemical durability in extreme ultraviolet environments, leading to contamination of masks and reduced productivity.
Innovation Solution
A pellicle layer formed with an M-α material, where M is Si, Zr, Mo, Ru, Y, W, Ti, or Nb, and α is B, N, C, O, or F, combined to form layers with high transmittance, thermal stability, and chemical durability, including a support, core, and capping layer structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional pellicle materials are used, then mask protection is provided, but extreme ultraviolet transmittance is insufficient and mask contamination occurs
Solution Approach 1:
The patent employs composite materials consisting of multiple layers with different compositions (e.g., SiO2, Si3N4, SiB6xN1-x, YB2xN1-x) to achieve both high extreme ultraviolet transmittance and mask protection. Each layer is designed with specific optical and mechanical properties that complement each other, allowing the pellicle to transmit 90% or more of extreme ultraviolet light while maintaining durability and preventing mask contamination.
2Strength
If pellicle material thickness is increased to improve mechanical stability, then mechanical strength is improved, but extreme ultraviolet transmittance decreases
Solution Approach 1:
The patent applies local quality by designing each layer of the pellicle with specific thicknesses and material compositions optimized for its particular function. The support layer, core layer, and capping layer each have different thickness ranges and material properties tailored to provide mechanical stability where needed while maintaining high transmittance in the optical path. This localized optimization allows the pellicle to achieve both mechanical strength and high extreme ultraviolet transmittance without requiring uniform thickness increases throughout the entire structure.
3Illumination intensity
If pellicle material is optimized for high transmittance, then extreme ultraviolet transmittance is improved, but thermal stability and chemical durability are reduced
Solution Approach 1:
The patent uses composite materials with multiple layers having different thermal and chemical properties. The core layer contains materials like SiB6xN1-x and YB2xN1-x that provide both high extreme ultraviolet transmittance and thermal stability. The capping layer uses materials with high chemical durability to protect the underlying layers. This composite structure allows the pellicle to simultaneously achieve 90% or more extreme ultraviolet transmittance while maintaining stability in the extreme ultraviolet output environment of 350 W or more.
4Ease of manufacture
If single-layer pellicle structure is used to simplify manufacturing, then manufacturing complexity is reduced, but performance requirements for transmittance and stability cannot be met
Solution Approach 1:
The patent segments the pellicle into multiple functional layers (support layer, core layer, capping layer, and optionally intermediate layers) that can be manufactured and optimized independently. Each layer serves a specific function: the support layer provides mechanical strength, the core layer optimizes optical properties for high transmittance, and the capping layer provides environmental protection. This segmentation allows each layer to be tailored to specific performance requirements while maintaining a systematic manufacturing approach that is feasible for industrial production.
Data Source
AI summary
This application relates to a pellicle for extreme ultraviolet lithography used in a lithography process using extreme ultraviolet rays. In one aspect, the pellicle includes a pellicle layer formed of an M-α material in which M is combined with α. Here, M is one of Si, Zr, Mo, Ru, Y, W, Ti, Ir, or Nb, and α is at least two of B, N, C, O, or F.