EUV Mirror Ultra-smooth Layer for Phase Defect Reduction
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Solution Overview
Problem
Extreme ultraviolet lithography systems face challenges with phase defects caused by scratches and surface variations on substrates, which are magnified due to the short wavelengths used, leading to irreparable damage in semiconductor devices, as existing techniques like polishing and annealing introduce new imperfections or surface roughness.
Innovation Solution
A system involving a planarization layer followed by an ultra-smooth layer with reorganized molecules, and a multi-layer stack with an amorphous metallic layer and capping layers is used to create an atomically flat and defect-free surface for EUV lens elements and mask blanks, utilizing deposition techniques like CVD and PVD to fill pits and bury defects, and further smoothing with methods like CMP or annealing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If mechanical polishing with abrasive is used to smooth the substrate surface, then surface roughness is reduced, but scratch-dig marks are introduced which cause phase defects in EUV lithography
Solution Approach 1:
The harmful scratch-dig marks generated by mechanical polishing are completely removed by selectively etching them using oxygen plasma or chemical etchants, while preserving the overall surface smoothness achieved by polishing
Solution Approach 2:
The surface treatment transitions from mechanical polishing alone to a combined process of polishing followed by selective chemical or plasma etching, changing the physical-chemical parameters of the surface to eliminate scratches while maintaining smoothness
2Manufacturing precision
If laser or plasma annealing is used to smooth the substrate surface, then surface uniformity is improved, but longer range roughness or ripples are induced which do not provide required flatness
Solution Approach 1:
Thermal or plasma-based annealing processes are replaced with oxygen plasma treatment or chemical etching processes that use chemical reactions rather than thermal energy to smooth the surface, avoiding the induction of long-range roughness
Solution Approach 2:
The surface smoothing mechanism changes from thermal annealing to chemical or plasma-based processes, altering the physical-chemical parameters to achieve smoothness without creating ripples
3Object-generated harmful factors
If conventional cleaning techniques are used to remove particles, then particle defects are reduced, but new pits are generated or existing pits are amplified
Solution Approach 1:
The oxygen plasma process that is used to smooth the surface also simultaneously removes particle defects and fills pits, converting a potential harmful process into a beneficial one that addresses multiple defect types
4Object-generated harmful factors
If multiple processing steps are used to reduce defects, then defect density is reduced, but process complexity increases and new imperfections may be introduced
Solution Approach 1:
Multiple defect reduction functions (particle removal, pit filling, surface smoothing) are merged into a single oxygen plasma treatment step, reducing process complexity while maintaining defect reduction effectiveness
Solution Approach 2:
The oxygen plasma process serves multiple functions simultaneously: it smooths the surface, removes particle defects, and fills pits, making it a universal treatment that addresses various defect types in one step
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
This approach results in an atomically flat, low-defect surface for EUV lens elements and mask blanks, reducing phase defects and enabling the production of high-quality semiconductor devices by minimizing surface imperfections, thus addressing the critical need for smaller feature sizes and improving manufacturing efficiency and cost-effectiveness.
Implementation Method 1
utilizing deposition techniques like CVD and PVD to fill pits and bury defects
Implementation Method 2
further smoothing with methods like CMP or annealing
Data Source
AI summary
An extreme ultraviolet mirror or blank production system includes: a first deposition system for depositing a planarization layer over a semiconductor substrate; a second deposition system for depositing an ultra-smooth layer over the planarization layer, the ultra-smooth layer having reorganized molecules; and a third deposition system for depositing a multi-layer stack over the ultra-smooth layer. The extreme ultraviolet blank includes: a substrate; a planarization layer over the substrate; an ultra-smooth layer over the planarization layer, the ultra-smooth layer having reorganized molecules; a multi-layer stack; and capping layers over the multi-layer stack. An extreme ultraviolet lithography system includes: an extreme ultraviolet light source; a mirror for directing light from the extreme ultraviolet light source; a reticle stage for placing an extreme ultraviolet mask blank with a planarization layer and an ultra-smooth layer over the planarization layer; and a wafer stage for placing a wafer.