Metal-Containing Sidewall Passivation for High Aspect Ratio Cylinder Etch
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Solution Overview
Problem
Conventional etching processes for high aspect ratio cylinders in dielectric materials suffer from non-uniform etching profiles due to inadequate sidewall protection, leading to over-etching and compromised structural integrity, as existing fluorocarbon-based processes struggle to form protective polymeric sidewall coatings deep within the feature.
Innovation Solution
A method involving the deposition of a metal-containing protective film, such as tungsten nitride, along the sidewalls of the etched feature using atomic layer deposition or chemical vapor deposition, which prevents lateral etching and maintains a uniform profile by ensuring conformal coverage throughout the feature's depth.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If fluorocarbon-based etching processes are used, then etching can proceed, but inadequate sidewall protection occurs leading to non-uniform etching profiles
Solution Approach 1:
A metal-containing protective film (such as tungsten nitride, titanium nitride, or tantalum nitride) is deposited on the sidewalls of the etched feature to serve as an intermediary protective layer. This film prevents lateral etching of the sidewalls while allowing the etching process to proceed, thereby achieving uniform etching profiles with proper sidewall protection.
Solution Approach 2:
The metal-containing protective film is deposited on the sidewalls before the etching process completes. This preliminary protection ensures that sidewalls are safeguarded against lateral etching during the etching process, preventing non-uniform profiles and over-etching.
2Productivity
If conventional etching processes are used, then etching speed is maintained, but over-etching occurs compromising structural integrity
Solution Approach 1:
The metal-containing protective film acts as a mediator that protects the sidewalls during high-rate etching processes. This allows maintaining high etching rates while preventing over-etching that would compromise the structural integrity of the etched features.
Solution Approach 2:
The introduction of metal-containing protective films changes the etching process parameters by adding a protective layer that modifies the etching behavior. This enables higher etching rates to be achieved without the harmful side effect of over-etching, thereby maintaining both productivity and structural integrity.
3Manufacturing precision
If fluorocarbon-based processes are used, then etching can proceed, but protective polymeric sidewall coatings fail to form deep within the feature
Solution Approach 1:
The patent changes the material parameter of the protective coating from fluorocarbon-based polymeric material to metal-containing material (such as tungsten nitride, titanium nitride, or tantalum nitride). This parameter change enables the protective coating to be deposited conformally deep within high aspect ratio features, achieving uniform sidewall protection throughout the feature depth.
Solution Approach 2:
The metal-containing protective film serves as an intermediary material that overcomes the limitations of fluorocarbon-based coatings. This intermediary material can be deposited conformally on sidewalls deep within features and provides reliable protection against lateral etching, solving the formation difficulty of deep sidewall coatings.
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 formation of high aspect ratio features with reduced bow and improved vertical etch rates, maintaining uniform critical dimensions and structural integrity by effectively preventing over-etching and enhancing sidewall protection.
Implementation Method 1
depositing a protective film on sidewalls of the feature, the protective film including a metal, where the protective film is deposited along substantially the entire depth of the feature
Implementation Method 2
depositing a protective film on sidewalls of the feature through a chemical vapor deposition reaction
Implementation Method 3
generating a first plasma including an etching reactant, exposing the substrate to the first plasma, and partially etching the feature in the dielectric-containing stack
Data Source
AI summary
Various embodiments herein relate to methods, apparatus and systems for forming a recessed feature in a dielectric-containing stack on a semiconductor substrate. Separate etching and deposition operations are employed in a cyclic manner. Each etching operation partially etches the feature. Each deposition operation forms a protective coating (e.g., a metal-containing coating) on the sidewalls of the feature to prevent lateral etch of the dielectric material during the etching operations. The protective coating may be deposited using methods that result in formation of the protective coating along substantially the entire length of the sidewalls. The protective coating may be deposited using particular reaction mechanisms that result in substantially complete sidewall coating. Metal-containing coatings have been shown to provide particularly good resistance to lateral etch during the etching operation. In some cases, a bilayer approach may be used to deposit the protective coating on sidewalls of partially etched features.