HF-NH3 Gas Etching of Three-Layer Oxide-Nitride Films
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Solution Overview
Problem
Existing methods struggle to efficiently and selectively etch a three-layered film composed of a first silicon oxide-based film, a silicon nitride-based film, and a second silicon oxide-based film without generating plasma, particularly in semiconductor manufacturing processes.
Innovation Solution
An etching method using a HF-NH3-based gas mixture is employed to collectively etch the three-layered film, adjusting gas ratios and temperatures to achieve selective etching of each film layer, with a cycle etching process to manage reaction products.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a HF-NH3-based gas is used for collective etching of the three-layered film, then productivity is improved by enabling simultaneous etching of multiple films, but manufacturing precision deteriorates due to difficulty in achieving selective etching of each film layer
Solution Approach 1:
The patent applies dynamics by making the gas ratio adjustable during the etching process. The gas supply system allows dynamic adjustment of the HF and NH3 gas flow rates to optimize etching conditions for different film layers. This enables the system to adapt to different etching requirements (silicon oxide vs. silicon nitride) while maintaining collective etching capability, thus resolving the contradiction between productivity and manufacturing precision.
Solution Approach 2:
The patent utilizes parameter changes by varying the gas ratio (HF:NH3 proportion) to achieve selective etching. By changing the concentration parameters of the etching gases, the system can selectively remove silicon oxide films while preserving silicon nitride films, or etch silicon nitride when needed. This parameter adjustment mechanism enables high selectivity while maintaining the productivity benefits of collective etching.
2Manufacturing precision
If the gas ratio is adjusted to enhance etching of silicon oxide films, then manufacturing precision is improved by achieving better selectivity, but productivity deteriorates due to slower overall etching speed
Solution Approach 1:
The patent applies periodic action by implementing cyclic etching processes where the gas ratio is periodically adjusted. The system alternates between gas compositions optimized for silicon oxide etching and those optimized for silicon nitride etching. This periodic adjustment allows each film layer to be etched at its optimal rate while maintaining overall process efficiency, thus resolving the contradiction between selectivity and throughput.
Solution Approach 2:
The dynamic gas ratio adjustment capability allows the system to optimize etching conditions in real-time. When silicon oxide etching is needed, the gas composition is adjusted to favor oxide removal; when silicon nitride etching is needed, the composition shifts accordingly. This dynamic adaptability ensures high selectivity without permanently sacrificing overall etching speed.
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 method enables high selectivity and throughput in etching the three-layered film, minimizing material loss and ensuring precise exposure of underlying layers, particularly suitable for semiconductor manufacturing.
Implementation Method 1
the HF gas and the NH3 gas react with the silicon oxide film to generate ammonium fluorosilicate
Implementation Method 2
the silicon oxide film is etched by sublimating the ammonium fluorosilicate by heating
Data Source
AI summary
An etching method includes: providing, to an interior of a chamber, a substrate having a three-layered film formed by stacking a first silicon oxide-based film, a silicon nitride-based film, and a second silicon oxide-based film; and collectively etching the three-layered film using a HF—NH3-based gas in the interior of the chamber while adjusting a gas ratio in each of the first silicon oxide-based film, the silicon nitride-based film, and the second silicon oxide-based film.