EUV Mask Blank Bi-Layer Absorber for Shadowing Reduction
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Solution Overview
Problem
Extreme ultraviolet lithography systems face challenges with opaque, clear, and phase defects due to material absorption and surface imperfections, limiting feature size and efficiency in semiconductor manufacturing, particularly with thicker absorbers causing shadowing issues as feature sizes decrease.
Innovation Solution
An integrated EUV mask blank production system with a substrate handling vacuum chamber and multiple sub-chambers for forming a multi-layer stack and a bi-layer absorber, using ultra-low expansion substrates, planarization layers, and specific absorber materials like silver and nickel to achieve low reflectivity and minimize defects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a thicker absorber is used, then light absorption is improved, but shadowing issues occur that limit feature size
Solution Approach 1:
The patent changes the material composition and thickness parameters of the absorber layer, transitioning from traditional thick absorbers to a thin bi-layer structure with optimized thickness and material properties to achieve sufficient absorption without shadowing
Solution Approach 2:
The patent employs a bi-layer absorber structure combining different materials (such as silver and nickel layers) to achieve superior light absorption performance in a thin configuration, avoiding the shadowing problems of single-material thick absorbers
2Ease of manufacture
If traditional absorber materials are used, then manufacturing is simpler, but reflectivity is too high for sub-0.0135 micron features
Solution Approach 1:
The patent modifies the optical parameters of the absorber by selecting materials with higher absorption coefficients at 13.5 nm wavelength and optimizing layer thickness to achieve reflectivity below 1.9%, enabling sub-0.0135 micron feature fabrication
Solution Approach 2:
The patent uses a bi-layer absorber design where the combination of materials and thicknesses is optimized to copy the desired optical absorption characteristics needed for advanced node lithography
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 system produces EUV mask blanks with ultra-low defects, enabling the fabrication of smaller feature sizes by reducing shadowing and reflectivity, improving manufacturing efficiency and reducing costs through precise control of absorber thickness and material selection.
Implementation Method 1
a first sub-chamber for forming a multi-layer stack, above the ultra-low expansion substrate, for reflecting an extreme ultraviolet (EUV) light
Implementation Method 2
a second sub-chamber for forming a bi-layer absorber, formed above the multi-layer stack, for absorbing the EUV light at a wavelength of 13.5 nm
Data Source
AI summary
An extreme ultraviolet (EUV) mask blank production system includes: a substrate handling vacuum chamber for creating a vacuum; a substrate handling platform, in the vacuum, for transporting an ultra-low expansion substrate loaded in the substrate handling vacuum chamber; and multiple sub-chambers, accessed by the substrate handling platform, for forming an EUV mask blank includes: a first sub-chamber for forming a multi-layer stack, above the ultra-low expansion substrate, for reflecting an extreme ultraviolet (EUV) light; and a second sub-chamber for forming a bi-layer absorber, formed above the multi-layer stack, for absorbing the EUV light at a wavelength of 13.5 nm provides a reflectivity of less than 1.9%.