Graphite Pellicle Fabrication for EUV Photomask Protection
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Solution Overview
Problem
Particle contamination is a significant issue in semiconductor manufacturing, particularly in extreme ultra violet (EUV) photolithography processes, where existing pellicle technologies fail to provide adequate protection for photomasks.
Innovation Solution
The development of free-standing pellicles with a single graphite layer, fabricated by forming a graphite layer on a substrate, creating a stack with a supporting layer, separating from the substrate, and transferring it onto a frame, while removing the supporting layer to minimize contamination and enhance durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a pellicle is used to protect photomasks from particle contamination, then contamination protection is improved, but the pellicle itself becomes a source of contamination and defects
Solution Approach 1:
The patent changes the material parameter of the pellicle from traditional transparent materials to graphite material. Graphite's unique properties (chemically inert, thermally stable, electron-repulsive) fundamentally alter how the pellicle interacts with contaminants and EUV light, transforming it from a potential contamination source to a protective barrier that actively repels contaminants while maintaining optical performance
Solution Approach 2:
The invention uses graphite as a composite material layer in the pellicle structure. Graphite's composite nature—combining mechanical strength, chemical inertness, thermal stability, and electron repulsion—creates a multi-functional protective layer that simultaneously addresses contamination protection, optical transmittance, and durability requirements
2Reliability
If existing pellicle technologies are used, then basic protection is provided, but physical and chemical durability is insufficient for EUV processes
Solution Approach 1:
The patent fundamentally changes the material composition parameter from organic polymers to inorganic graphite material. This parameter change confers superior thermal stability, chemical inertness, and mechanical durability, enabling the pellicle to withstand the harsh EUV processing environment for extended periods without degradation
Solution Approach 2:
The patent inverts this principle by creating a permanent, non-disposable pellicle. The graphite layer's exceptional stability and resistance to degradation allow it to serve as a long-lasting protective component throughout the photomask's operational life, eliminating the need for frequent replacement
3Object-affected harmful factors
If a pellicle is added to protect against particles, then contamination protection is improved, but light transmittance is reduced
Solution Approach 1:
The patent changes the optical parameter of the pellicle material. Graphite's unique optical properties allow it to transmit EUV light effectively while providing robust particle protection, unlike traditional materials that block EUV radiation. This parameter change resolves the contradiction between protection and transmittance
4Ease of manufacture
If traditional pellicle materials are used, then ease of manufacture is maintained, but resistance to electron bombardment is insufficient
Solution Approach 1:
The patent changes the electrical parameter of the pellicle material by using graphite, which has electron-repulsive properties. This parameter change provides inherent protection against electron bombardment during EUV processing while maintaining compatibility with existing manufacturing techniques for depositing thin films
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 graphite pellicles offer improved physical and chemical durability, high light transmittance, and a repulsive force against electrons, effectively reducing contamination and defects in EUV photolithography processes.
Implementation Method 1
a repulsive force against electrons, effectively reducing contamination and defects in EUV photolithography processes
Data Source
AI summary
The method includes forming a graphite layer on a substrate, forming a supporting layer on the graphite layer to form a stack of the graphite layer and the supporting layer, removing the substrate to separate the stack from the substrate, transferring the stack of the graphite layer and the supporting layer onto a frame, and removing the supporting layer from the frame.