Mask Encapsulation for High-Aspect-Ratio Etch CD Control
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Solution Overview
Problem
Current semiconductor fabrication processes struggle to achieve extremely high aspect ratio features with tight critical dimension control due to lateral etching, twisting, and bowing of sidewalls, which can lead to electrical shorting and surface irregularities.
Innovation Solution
A semiconductor process involving vertical etching and deposition of an amorphous carbon liner on the sidewalls of features, with iterative cycles of etching and liner deposition to maintain tight CD control and prevent lateral etching.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If conventional metal-based or carbon-based polymer liners are used to prevent lateral etching, then protection against sidewall bowing is improved, but surface irregularities, striations, and kinking occur on the sidewalls
Solution Approach 1:
The patent changes the material parameters of the liner from conventional metal-based or carbon-based polymers to amorphous carbon deposited under specific conditions (low ion bombardment, low substrate temperature) to achieve a smoother, more uniform sidewall surface while maintaining lateral etching protection
Solution Approach 2:
The patent creates a composite structure by depositing amorphous carbon as a liner material that combines the protective function against lateral etching with the smooth surface quality needed for precise feature fabrication, eliminating the trade-off between protection and surface irregularities
2Reliability
If the liner material is highly resistant to etch chemistries, then protection against lateral etching is improved, but striations and kinking occur on the sidewalls
Solution Approach 1:
The patent modifies the deposition parameters (reducing ion bombardment energy and substrate temperature) to create an amorphous carbon liner that is sufficiently resistant to etch chemistries while avoiding the formation of striations and kinking, achieving both reliability and precision
3Reliability
If feature spacing is increased to avoid electrical shorting from sidewall bowing, then reliability is improved, but device density decreases
Solution Approach 1:
The patent uses a thin amorphous carbon liner film that provides effective protection against lateral etching and sidewall bowing, enabling tighter feature spacing while maintaining electrical isolation, thus improving device density without sacrificing reliability
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 process enables the fabrication of deep features with extremely high aspect ratios and tight critical dimension control, minimizing lateral etching and surface irregularities, thus improving the density and quality of semiconductor devices.
Implementation Method 1
depositing an amorphous carbon liner onto the sidewalls of the feature
Data Source
AI summary
A tool and method for processing substrates by encapsulating a mask to protect from degradation during an etch-back to prevent a feature liner material from pinching off an opening during deposition-etch cycles used to fabricate high aspect ratio features with very tight critical dimension control.