Mo-W Interconnect Filling for Low-Resistivity Semiconductor Contacts
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Solution Overview
Problem
The deposition of low resistivity metal films in semiconductor fabrication processes becomes challenging as devices shrink and more complex patterning schemes are utilized, particularly in filling features of varying sizes with metals like molybdenum and tungsten.
Innovation Solution
A method involving atomic layer deposition (ALD) of molybdenum (Mo) followed by chemical vapor deposition (CVD) or physical vapor deposition (PVD) of tungsten (W) is employed to fill features of different critical dimensions, allowing for efficient filling of both small and large features with low resistivity metals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional deposition methods are used to fill features of varying sizes, then filling of large features is achieved, but filling precision and uniformity in small features deteriorates
Solution Approach 1:
The deposition process is segmented into two distinct stages: ALD for precise filling of small features and CVD for efficient filling of large features. This segmentation allows each method to optimize its performance for specific feature size ranges, achieving both high precision and broad adaptability across varying feature dimensions.
Solution Approach 2:
Different deposition methods are applied to different spatial regions based on feature size: ALD is used for small features where conformal coverage and precision are critical, while CVD is used for large features where deposition speed and efficiency are prioritized. This local quality approach ensures optimal filling performance for each feature type.
2Manufacturing precision
If ALD is used to fill all features, then filling precision is improved, but deposition time and productivity worsen
Solution Approach 1:
The feature population is segmented by size, with ALD applied only to small features requiring high precision and CVD applied to large features where speed is more important. This segmentation maintains high filling precision for critical small features while significantly improving overall productivity by using faster CVD methodology for larger features.
Solution Approach 2:
The deposition strategy applies different quality levels to different feature types: high-precision ALD for small features and high-speed CVD for large features. This local quality differentiation optimizes the balance between precision and productivity by matching deposition method characteristics to feature-specific requirements.
3Productivity
If CVD is used to fill all features, then deposition speed is improved, but filling uniformity and precision in small features worsens
Solution Approach 1:
Features are segmented by size to determine appropriate deposition method: small features receive ALD treatment for uniform conformal coverage, while large features receive CVD treatment for rapid filling. This segmentation ensures that small features achieve the necessary filling uniformity while overall productivity is maintained through efficient CVD processing of large features.
Solution Approach 2:
The deposition process delivers different quality characteristics to different feature types: ALD provides superior conformal coverage and uniformity for small features, while CVD provides high-speed deposition for large features. This local quality approach resolves the contradiction by ensuring each feature type receives the appropriate deposition quality for its specific requirements.
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 enables the efficient and scalable deposition of low resistivity metallization stacks, effectively addressing the challenge of filling features of varying sizes with high precision and low resistance, thereby improving the performance of semiconductor devices.
Implementation Method 1
depositing a bulk layer of molybdenum (Mo) by atomic layer deposition (ALD)
Implementation Method 2
depositing a bulk layer of tungsten (W) on the bulk layer of Mo by chemical vapor deposition (CVD) or physical vapor deposition (PVD)
Implementation Method 3
depositing a bulk layer of tungsten (W) on the bulk layer of Mo by chemical vapor deposition (CVD) or physical vapor deposition (PVD)
Data Source
AI summary
Metallization schemes involve atomic layer deposition (ALD) of molybdenum (Mo) and in some embodiments, ALD of Mo in a feature without a barrier layer. In some embodiments, deposition of the ALD Mo film may be followed by chemical vapor deposition (CVD) or physical vapor deposition (PVD) of a Mo film. In some embodiments, the CVD or PVD Mo film is part of the metallization stack. In other embodiments, the CVD or PVD Mo film is deposited as a sacrificial overburden layer. In some embodiments, deposition of the ALD Mo film may be followed by CVD or PVD of another metal such as tungsten (W). In some embodiments, the CVD or PVD W film is part of the metallization stack. In other embodiments, the CVD or PVD W film is deposited as a sacrificial overburden layer.