Sidewall Passivation Chemistry for High-Aspect-Ratio Dielectric Etch
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Solution Overview
Problem
The challenge in semiconductor fabrication is etching high aspect ratio features in dielectric materials, where existing technologies struggle to achieve uniformity due to insufficient protection of sidewalls during etching, leading to non-uniform profiles and structural integrity issues.
Innovation Solution
The method involves depositing a protective film on the sidewalls of etched features using reactants with aldehyde or isocyanate functional groups, which prevents lateral etching and allows for high aspect ratio etching by forming an organic polymeric film through cyclic adsorption and reaction processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional etching methods are used for high aspect ratio features, then etching depth can be achieved, but sidewall protection is insufficient leading to non-uniform profiles
Solution Approach 1:
The patent applies preliminary action by depositing the protective film on the sidewalls before the lateral etching process begins. This protective film is formed through cyclic adsorption of reactants (such as fluorocarbon species) onto the sidewall surfaces, creating a protective layer that prevents excessive lateral etching and maintains profile uniformity throughout the etching process.
Solution Approach 2:
The patent implements local quality by providing differentiated protection to different regions of the etched feature. The protective film is selectively deposited on the sidewalls where protection is needed, while allowing the etching front to proceed uniformly at the bottom. This localized protection ensures that sidewalls maintain their structural integrity and uniformity without compromising the overall etching depth and profile.
2Manufacturing precision
If reactants are used to deposit protective film on sidewalls, then lateral etch is prevented, but process complexity increases
Solution Approach 1:
The patent merges the protective film deposition process with the existing etching process by using the same reactants (fluorocarbon species) that are already present in the etching plasma. This integration allows the protective film to be deposited on sidewalls during the etching process itself, rather than requiring separate deposition and etching steps, thereby reducing overall process complexity while maintaining sidewall protection.
Solution Approach 2:
The patent applies self-service by utilizing the etching reactants themselves to form the protective film on the sidewalls. The fluorocarbon species that are used to etch the dielectric material also adsorb onto the sidewall surfaces and polymerize to form a protective layer. This self-protecting mechanism eliminates the need for external protective coatings or additional process steps, simplifying the overall manufacturing process.
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 etched features with aspect ratios of 5 or greater, maintaining uniformity and preventing structural compromises by effectively protecting sidewalls from over-etching.
Implementation Method 1
exposing the substrate to a first reactant and allowing the first reactant to adsorb onto the substrate, where the first reactant includes an aldehyde functional group
Implementation Method 2
exposing the substrate to a second reactant, where the first and second reactants react with one another to form the protective film
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 material
Data Source
AI summary
Various embodiments herein relate to methods. apparatus and systems for forming a recessed feature in dielectric material 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 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 the sidewalls. In some cases. the protective coating is deposited using molecular layer deposition techniques. The protective coating may be deposited using particular reactants that result in relatively complete sidewall coating at relatively low temperatures. In some implementations. one or more of the reactants include an aldehyde functional group. In some implementations. one or more of the reactants include an isocyanate functional group.