Selective Polysilicon Etching Using FNO and F2 Gas Mixture
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Solution Overview
Problem
Current non-plasma dry etching techniques, such as those using a mixed gas of HF and F2, face challenges in achieving high etching rates and selectivity for silicon in semiconductor manufacturing, particularly when etching polysilicon films compared to silicon nitride films, which hinders their adoption in mass production.
Innovation Solution
A method involving the use of FNO and F2 gases diluted with an inert gas, such as nitrogen, is employed to react with silicon on a substrate, optimizing conditions like temperature and pressure to achieve high etching selectivity and rate, specifically targeting polysilicon films while minimizing etching of silicon nitride films.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a mixed gas of HF gas and F2 gas is used for etching silicon, then etching can be performed, but the etching rate is considerably reduced
Solution Approach 1:
The patent changes the chemical composition parameters of the etching gas from conventional HF/F2 mixed gas to a gas containing NF3 and F2. This parameter change in gas composition enables simultaneous achievement of high etching rate and high etching selectivity for silicon, resolving the technical contradiction between productivity and reliability.
2Reliability
If conventional etching methods are used, then processing can be performed, but etching selectivity between polysilicon and silicon nitride is insufficient
Solution Approach 1:
The patent modifies the etching gas composition to include NF3 and F2, which creates a chemical environment that selectively attacks polysilicon while leaving silicon nitride largely unaffected. This parameter change achieves high etching selectivity (polysilicon etching rate much higher than silicon nitride), enabling faster processing without compromising selectivity.
Solution Approach 2:
The NF3 and F2 gases act as intermediary substances that facilitate selective chemical reactions. The gas composition serves as a mediator that enables differential etching rates between polysilicon and silicon nitride, allowing the etching process to distinguish between different materials on the substrate.
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 high-speed etching of polysilicon films with high selectivity compared to silicon nitride films, significantly reducing etching time and improving processing efficiency, allowing for faster production without excessive wear on equipment.
Implementation Method 1
supplying an FNO gas and an F2 gas that are diluted with an inert gas into the chamber such that the FNO gas and the F2 gas are reacted with the portion of silicon existing on the surface of the substrate to be processed
Data Source
AI summary
Provided is a method of selectively etching a portion of silicon existing on a surface of a substrate to be processed, which includes: loading the substrate to be processed into a chamber; and supplying an FNO gas and an F2 gas that are diluted with an inert gas into the chamber such that the FNO gas and the F2 gas are reacted with the portion of silicon existing on the surface of the substrate to be processed.