Selective Silicon Oxide Etching by Alternating COR and Purge Cycles
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Solution Overview
Problem
Current substrate-processing methods fail to achieve a high selectivity etching ratio between silicon oxide and silicon nitride films, leading to inefficient etching processes.
Innovation Solution
A substrate-processing method involving alternating cycles of chemical oxide removal (COR) using a gas mixture of fluorine-containing and basic gases, followed by purging with inert gas, to selectively etch silicon oxide films while minimizing etching of silicon nitride films.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a gas mixture of hydrogen fluoride gas and ammonia gas is used to etch silicon oxide film, then etching capability is improved, but selectivity etching ratio with respect to silicon nitride film deteriorates
Solution Approach 1:
The continuous etching process is segmented into alternating cycles: a first period where fluorine-containing gas etches silicon oxide, and a second period where basic gas removes etching residues. This segmentation prevents prolonged exposure of silicon nitride to etching conditions, improving selectivity.
Solution Approach 2:
The patent implements periodic alternation between etching mode (fluorine-containing gas supply) and residue removal mode (basic gas supply). This periodic action allows controlled etching of silicon oxide while periodically clearing residues that would otherwise continue to etch silicon nitride, thereby improving the selectivity etching ratio.
2Manufacturing precision
If etching time is extended to remove silicon oxide film completely, then etching completeness is improved, but etching of silicon nitride film increases
Solution Approach 1:
Basic gas acts as an intermediary substance that removes etching residues without significantly etching silicon nitride. By introducing this intermediary removal step, the system can achieve complete silicon oxide removal through repeated cycles while minimizing direct prolonged exposure of silicon nitride to aggressive etching conditions.
Solution Approach 2:
Repeated periodic cycles of etching followed by residue removal enable progressive elimination of silicon oxide without cumulative damage to silicon nitride. Each cycle removes a portion of the oxide and clears residues, preventing the need for extended continuous etching that would harm silicon nitride.
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 increases the selectivity etching ratio of silicon oxide films with respect to silicon nitride films by controlling etching rates, allowing for precise removal of silicon oxide films without significantly etching silicon nitride films.
Implementation Method 1
supplying a gas mixture to the surface of the substrate, thereby etching the silicon oxide film, the gas mixture including fluorine-containing gas and basic gas
Implementation Method 2
the gas mixture including fluorine-containing gas and basic gas
Data Source
AI summary
A substrate-processing method includes a) providing a substrate including a silicon oxide film on a surface of the substrate, b) supplying a gas mixture to the surface of the substrate, thereby etching the silicon oxide film, the gas mixture including fluorine-containing gas and basic gas, c) purging the surface of the substrate, and d) alternatingly repeating b) and c).