Sulfur Protective Layer for Sidewall Etching Precision
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Solution Overview
Problem
Current plasma etching methods for silicon-containing films often result in excessive lateral etching on the side walls of substrates, which can lead to unwanted surface modifications and reduced precision in film processing.
Innovation Solution
A method involving the formation of a protective layer containing sulfur atoms on the side walls of substrates, followed by controlled plasma etching to increase the depth of recesses without significant lateral etching, using sequential film deposition cycles and specific gas compositions to enhance the resistance of the protective layer to etching species.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If plasma etching is performed on silicon-containing films using fluorocarbon process gases, then etching of the film is achieved, but excessive lateral etching occurs on the side walls of the substrate
Solution Approach 1:
A protective layer containing sulfur atoms is formed on the side wall surface before the plasma etching process. This preliminary protective coating prevents the etching species from attacking the side walls during subsequent etching operations, thereby eliminating lateral etching while maintaining vertical etching precision
Solution Approach 2:
The sulfur-containing protective layer acts as an intermediary barrier between the etching species and the substrate side walls. This intermediate layer selectively protects the side walls from chemical attack by the fluorocarbon-based etching plasma, allowing precise control of etching morphology
2Manufacturing precision
If conventional plasma etching is used to increase recess depth, then film etching is achieved, but surface damage and unwanted modifications occur on side walls
Solution Approach 1:
The protective layer is deposited on the side wall surface before the plasma etching process begins. This pre-formed protective coating shields the side wall surface from damage and unwanted modifications during the etching process, enabling precise film processing without surface degradation
Solution Approach 2:
The sulfur-containing protective layer serves as a consumable sacrificial layer that protects the side walls during etching. This temporary protective coating can be easily removed or decomposed after serving its protective function, leaving the side wall surface intact and undamaged
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 effectively reduces lateral etching on the side walls, allowing for precise control of film depth and minimizing surface damage during the etching process, thereby improving the accuracy and efficiency of film processing.
Implementation Method 1
The protective layer contains sulfur atoms and is highly resistant to a chemical species used for etching the film
Implementation Method 2
Plasma etching is used for, for example, silicon-containing films. Plasma etching of silicon-containing films uses process gases containing a fluorocarbon gas
Data Source
AI summary
A technique enables etching of a film on a substrate with reduced etching on the surface of a side wall. An etching method includes forming a protective layer on a surface of a side wall defining a recess in a substrate. The protective layer contains sulfur atoms. The etching method further includes etching a film on the substrate to increase a depth of the recess after forming the protective layer.