Etching Gas Composition for Vertical Micropattern Profile Control
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Solution Overview
Problem
In the manufacturing of semiconductor devices, particularly in vertically stacked three-dimensional structures, there is a challenge in achieving high etch selectivity and pattern linearity and verticality due to issues with line edge roughness (LER) and line width roughness (LWR) in the etching process.
Innovation Solution
An etching gas composition comprising a first organofluorine compound with 3 to 6 carbon atoms and an organosulfur compound with 1 to 4 sulfur atoms, including a carbon-fluorine bond and a carbon-sulfur bond, is used to improve etch selectivity and surface roughness, enhancing the linearity and verticality of patterns by forming a sulfur-containing passivation layer during the etching process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional etching gas compositions are used, then etching process can be performed, but etch selectivity is insufficient and pattern linearity and verticality are poor due to high surface roughness
Solution Approach 1:
The patent changes the chemical composition parameters of the etching gas by introducing specific organosulfur compounds (1,3-propanesultone, 1,4-butanesultone, or 2,5-dihydrothiophene) with controlled concentrations (0.1-100 sccm) mixed with fluorocarbon-based etching gases. This parameter modification enables the formation of sulfur-containing passivation layers that reduce surface roughness and improve pattern linearity and verticality during etching processes
Solution Approach 2:
The organosulfur compounds act as intermediary substances that form sulfur-containing passivation layers on the etched surface. These intermediary layers serve dual functions: they protect the mask pattern from erosion (improving selectivity) and smooth the etched surface (reducing roughness), thereby mediating between the etching process and the final pattern quality
2Length of moving object
If etching is performed to form high-aspect-ratio contacts, then contact depth is achieved, but bowing and tapering increase due to poor pattern profile control
Solution Approach 1:
The patent applies preliminary action by forming sulfur-containing passivation layers on the mask pattern sidewalls before the main etching process. This preliminary passivation layer formation prevents mask erosion and maintains pattern profile integrity throughout the deep etching process, enabling high-aspect-ratio contact formation without excessive bowing or tapering
3Manufacturing precision
If mask pattern is used during etching, then pattern transfer is achieved, but mask erosion occurs reducing etch selectivity
Solution Approach 1:
The patent implements beforehand cushioning by introducing organosulfur compounds that form protective sulfur-containing passivation layers on the mask pattern sidewalls prior to and during the etching process. This cushioning effect protects the mask from erosion by the fluorocarbon-based etching gas, maintaining etch selectivity and pattern transfer accuracy throughout the etching 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
The etching gas composition significantly reduces surface roughness, improving the linearity and verticality of patterns, leading to the formation of high-quality, high-aspect-ratio contacts with reduced bowing or tapering, and maintaining excellent etch selectivity between silicon compounds and amorphous carbon layers.
Implementation Method 1
forming a sulfur-containing passivation layer during the etching process
Implementation Method 2
etching gas composition including a first organofluorine compound and an organosulfur compound
Data Source
AI summary
An etching gas composition includes a first organofluorine compound having 3 to 6 carbon atoms, and an organosulfur compound having 1 to 4 sulfur atoms. The organosulfur compound may include a carbon-fluorine (C—F) bond, a carbon-sulfur (C—S) bond, at least one carbon-carbon double (—C═C—) bond. When the etching gas composition is used, excellent etch selectivity may be obtained, and the linearity and verticality of a pattern may be greatly increased by improving line edge roughness (LER) and line width roughness (LWR) due to an improvement in the roughness of an etched surface.