Halogen Fluoride Plasma Etching With Low-N2 Gas Composition
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Solution Overview
Problem
In semiconductor production, the use of halogen fluorides as etching gases leads to the generation of silicon nitride films during plasma etching, which hinders micromachining and reduces etching rates due to the presence of N2 in the etching gas, as it reacts with fluorinated silicon and silicon oxide, causing accumulation on the substrate.
Innovation Solution
The etching method employs a halogen fluoride with a nitrogen (N2) content of 1 vol % or less, using gases like ClF3, BrF5, IF3, IF7, ClF, BrF3, or IF5, and incorporates a diluent gas such as Ar, Ne, or Xe, with a focus on forming plasma to achieve anisotropic etching, thereby minimizing silicon nitride film generation and maintaining high etching efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If N2 is used as a diluent gas in halogen fluoride etching, then the etching gas can be stabilized, but silicon nitride film is generated and accumulates on the substrate, hindering micromachining
Solution Approach 1:
The patent removes N2 from the etching gas composition entirely, replacing it with inert gases such as Ar, Ne, Kr, or Xe. This extraction of the harmful N2 component prevents silicon nitride film generation while maintaining gas stability through the use of chemically inert alternative gases.
Solution Approach 2:
The patent employs inert gases (Ar, Ne, Kr, Xe) to create an inert atmosphere in the etching process. These gases do not react with silicon or silicon oxide to form nitride films, yet provide the necessary plasma generation and process stability, effectively replacing the harmful N2 environment with a benign inert one.
2Device complexity
If N2 is present in the etching gas, then the gas composition can be simplified, but the etching rate reduces due to halogen fluoride consumption by silicon nitride reaction
Solution Approach 1:
The patent extracts N2 from the gas composition to eliminate the side reaction that consumes halogen fluoride. By removing the source of silicon nitride formation, the halogen fluoride is preserved for productive etching reactions, thereby maintaining high etching rates.
Solution Approach 2:
The patent changes the compositional parameters of the etching gas by specifying N2 content to be 1 vol% or less (preferably 0.1 vol% or less). This parameter control prevents excessive silicon nitride formation while allowing some N2 tolerance in the halogen fluoride material itself.
3Productivity
If conventional PFCs and HFCs are used as etching agents, then the etching speed of SiO2 increases, but they have high GWP and are designated as emission control substances
Solution Approach 1:
The patent adopts halogen fluorides (ClF3, BrF5, IF3, IF7, ClF, BrF3, IF5, BrF) as alternative etching agents that have lower GWP compared to conventional PFCs and HFCs. These gases provide effective etching performance while being environmentally more acceptable, serving as sustainable replacements for the controlled substances.
Solution Approach 2:
The patent changes the chemical composition parameters by transitioning from carbon-based etching agents (PFCs/HFCs) to halogen fluoride-based agents. This parameter change in the etching gas chemistry maintains etching effectiveness while reducing the global warming impact.
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 allows for precise etching of silicon or silicon oxide films with reduced silicon nitride formation, enhancing micromachining capabilities and maintaining high etching rates by controlling N2 content in the halogen fluoride etching gas, thus addressing the challenges of precision and efficiency in semiconductor processing.
Implementation Method 1
In the dry etching method, plasma is generated in a vacuum space and micropatterns are formed on a substance surface on a molecular basis
Implementation Method 2
silicon nitride is generated by the reaction of the fluorinated silicon generated and the N2 when plasma-etching silicon and a silicon oxide film
Implementation Method 3
silicon nitride is generated by the reaction of the fluorinated silicon generated and the N2 when plasma-etching silicon and a silicon oxide film, and the generated silicon nitride accumulates on the substrate
Data Source
AI summary
A method for precise plasma etching of micropatterns on a silicon substrate containing silicon or additionally having a silicon oxide film. An etching method for plasma-etching a silicon substrate having silicon or a silicon oxide film using a halogen fluoride having a nitrogen (N2) content of 1 vol % or less as an etching gas. Also disclosed is a method for producing a semiconductor using the etching method.