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 integrated circuit 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.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the capping layer is cleaned after multiple uses, then particles are removed from the mask, but the capping layer becomes damaged
Solution Approach 1:
A protective coating is applied to the capping layer before it undergoes cleaning processes. This preliminary protective layer prevents damage during cleaning while allowing the cleaning to effectively remove particles, thus maintaining mask performance without compromising capping layer integrity.
Solution Approach 2:
A protective coating serves as an intermediary between the cleaning process and the capping layer. This intermediary layer absorbs the mechanical stress and chemical exposure during cleaning, protecting the underlying capping layer from damage while still allowing effective particle removal.
2Productivity
If the capping layer is exposed to environmental conditions, then the mask performs its function, but the capping layer undergoes oxidation
Solution Approach 1:
A protective coating creates an inert environment around the capping layer, shielding it from oxygen and other reactive environmental conditions. This allows the mask to be used extensively while the capping layer remains protected from oxidation, maintaining both productivity and compositional stability.
Solution Approach 2:
The protective coating acts as an intermediary barrier between the capping layer and the oxidizing environment. It allows the mask to function normally while preventing direct contact between the capping layer and environmental oxidants, thus maintaining composition stability during extended use.
3Reliability
If a protective coating is applied to the capping layer, then resistance to oxidation and damage increases, but the process complexity increases
Solution Approach 1:
The protective coating changes the surface parameters of the capping layer, specifically increasing its chemical inertness and mechanical durability. By modifying the surface properties rather than the bulk material, the coating enhances reliability while adding minimal structural complexity.
Solution Approach 2:
The mask structure becomes a composite system with the protective coating layered over the capping layer. This composite structure combines the functional properties of the original capping layer with the protective properties of the coating, achieving enhanced durability with relatively simple additive complexity.
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, extending its lifespan and maintaining mask effectiveness during normal use and cleaning processes.
Implementation Method 1
Introducing a secondary material with a smaller atomic number, such as nitrogen, into the capping layer through implantation
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.