EUV Mask Adhesion Layer Prevents Ru Crystallization
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Solution Overview
Problem
EUV masks used in semiconductor manufacturing suffer from defects such as non-continuous Ru capping layers and carbon contamination, leading to degraded critical dimension uniformity and reduced reflectivity, which adversely affect the performance of integrated circuits.
Innovation Solution
The introduction of an adhesion layer between the reflective multilayer structure and the Ru-based capping layer prevents Ru crystallization and intermixing with Si, ensuring a continuous capping layer and reducing carbon accumulation, thereby enhancing the stability and quality of the EUV mask.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a Ru-based capping layer is deposited directly on the reflective multilayer structure, then the capping layer provides oxidation protection, but the Ru crystallizes and intermixes with Si leading to non-continuous coverage and degraded CD uniformity
Solution Approach 1:
An adhesion layer comprising silicon oxide and silicon nitride is introduced between the reflective multilayer structure and the Ru-based capping layer. This intermediary layer prevents direct contact between Ru and Si, thereby preventing Ru crystallization and intermixing while maintaining continuous coverage and CD uniformity, while still allowing the Ru capping layer to provide oxidation protection.
2Ease of manufacture
If Ru is deposited directly on the top Si layer, then the capping process is simplified, but carbon from metal organic precursor residues accumulates in the Ru capping layer reducing reflectivity
Solution Approach 1:
The adhesion layer acts as a barrier between the reflective multilayer structure and the Ru-based capping layer, preventing carbon from metal organic precursor residues during Ru deposition from accumulating in the Ru capping layer. This intermediary barrier maintains low carbon content in the Ru layer, preserving high reflectivity while keeping the capping process relatively simple.
3Reliability
If the Ru capping layer is made continuous to prevent oxidation, then oxidation protection is improved, but Ru intermixing with Si degrades the interface quality
Solution Approach 1:
The adhesion layer comprising silicon oxide and silicon nitride serves as a physical barrier that prevents Ru atoms from intermixing with Si atoms at the interface during deposition. This intermediary layer allows the Ru capping layer to be deposited continuously for oxidation protection while maintaining a stable, non-intermixed interface composition between the Ru layer and the underlying Si layer.
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 use of an adhesion layer improves the uniformity of the capping layer and reduces carbon accumulation, resulting in improved stability and performance of the EUV mask, which enhances the quality and reliability of integrated circuits.
Implementation Method 1
The introduction of an adhesion layer between the reflective multilayer structure and the Ru-based capping layer prevents Ru crystallization and intermixing with Si
Implementation Method 2
reducing carbon accumulation, thereby enhancing the stability and quality of the EUV mask
Data Source
AI summary
A photolithography mask includes a substrate, a reflective multilayer structure over the substrate, an adhesion layer over the reflective multilayer structure, a capping layer over the adhesion layer, and a patterned absorber layer over the capping layer. The capping layer includes a non-crystalline conductive material.