EUV Mask Capping Layer Oxidation Resistance via Nitrogen Implantation
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Solution Overview
Problem
The capping layer of EUV masks in photolithography is prone to damage and oxidation due to cleaning processes and environmental exposure, which affects the longevity and performance of the masks during semiconductor fabrication.
Innovation Solution
Introducing a secondary material with a smaller atomic number, such as nitrogen, into the capping layer through implantation or during the dry etching process to enhance its resistance to oxidation and damage, thereby strengthening the capping layer and extending its lifespan.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the capping layer is cleaned periodically to remove particles, then the mask performance is maintained, but the capping layer suffers damage over time
Solution Approach 1:
The patent applies preliminary action by introducing a secondary material into the capping layer before damage occurs. This secondary material is embedded in the capping layer during fabrication, creating a strengthened structure that resists subsequent cleaning damage. The strengthening is performed in advance to prevent degradation during operational cleaning cycles.
2Adaptability or versatility
If the capping layer is exposed to environmental factors during use, then the mask operates in field conditions, but oxidation damages the capping layer
Solution Approach 1:
The patent employs composite materials by combining the original capping layer material with a secondary material having different properties. The secondary material is selected to provide oxidation resistance while maintaining compatibility with the capping layer structure. This composite structure allows the capping layer to withstand environmental factors during field operations.
Solution Approach 2:
The patent applies parameter changes by modifying the chemical composition of the capping layer through the introduction of a secondary material. This changes the material's resistance parameters, specifically increasing oxidation resistance and damage threshold, while maintaining the capping layer's protective function during field use.
3Ease of manufacture
If a single-material capping layer is used, then the manufacturing process is simple, but the layer is prone to oxidation and damage
Solution Approach 1:
The patent uses composite materials to enhance the capping layer's reliability. The secondary material is introduced during the capping layer formation process, creating a composite structure that provides superior oxidation resistance and damage resistance compared to single-material layers, while maintaining manufacturability through integration into the existing fabrication workflow.
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 treated capping layer is less susceptible to oxidation and other forms of damage, ensuring the EUV mask's effectiveness over a longer period and reducing the need for frequent cleaning and replacement.
Implementation Method 1
Introducing a secondary material with a smaller atomic number, such as nitrogen, into the capping layer through implantation or during the dry etching process
Data Source
AI summary
A method for forming a lithography mask includes forming a capping layer on a reflective multilayer layer, the capping layer comprising a first material, forming a patterned patterning layer on the capping layer, and introducing a secondary material into the capping layer, the secondary material having an atomic number that is smaller than 15.