Metal Fluoride Activated Carbon for HF Gas Purification
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Solution Overview
Problem
Existing methods for deep purification of HF electronic gas, such as adsorbents and rectification processes, are ineffective in removing moisture to the required ppb levels due to the strong reactivity and corrosivity of water-containing HF, which leads to secondary pollution and degradation of semiconductor device performance.
Innovation Solution
A metal fluoride-loaded activated carbon material (AC/MFx) is prepared through a method involving the dissolution of acetate in water, addition of disodium ethylenediaminetetraacetate, ammonium fluoride, and ammonia to adjust pH, followed by the incorporation of mesoporous activated carbon and sodium tetrafluoroborate. This material is then subjected to a crystallization reaction and deep dehydration using a mixed gas flow of carbonyl fluoride and high-purity nitrogen.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional rectification process and adsorbents are used to remove moisture from HF, then the purification process can be implemented, but the moisture content cannot be reduced to ppb levels due to secondary pollution and material degradation
Solution Approach 1:
The patent uses a composite material consisting of activated carbon supported metal fluoride particles. The activated carbon provides a stable carrier structure that prevents material degradation, while the metal fluoride component enables deep moisture removal to ppb levels. This composite structure resolves the contradiction by maintaining material stability while achieving the required purification precision without generating secondary pollution.
Solution Approach 2:
The patent employs porous activated carbon as the carrier material, which provides a large surface area and porous structure for supporting the metal fluoride particles. The porous structure enables efficient contact between the purification material and HF gas, facilitating deep moisture removal while the stable activated carbon framework prevents material degradation and secondary pollution.
2Productivity
If oxide adsorbents such as activated alumina, silica and silicon aluminum oxide molecular sieves are used to remove water from HF, then the adsorption process can proceed, but the adsorbents react with HF and cannot efficiently remove water
Solution Approach 1:
The patent uses activated carbon as an intermediary carrier material that is chemically stable and does not react with HF. The metal fluoride is loaded onto this stable carrier, allowing the system to achieve efficient water removal through the metal fluoride component while the activated carbon intermediary prevents the stability issues that would arise from using reactive oxide adsorbents directly.
Solution Approach 2:
The patent changes the chemical composition parameter of the adsorbent from conventional oxide-based materials to a composite of activated carbon supported metal fluoride. This parameter change transforms the material's chemical properties, making it resistant to HF while maintaining or enhancing water removal capability, thus resolving the contradiction between productivity and reliability.
3Reliability
If carbon-based materials such as activated carbon are used for moisture adsorption in HF, then the material is chemically stable, but the adsorption efficiency and capacity are limited
Solution Approach 1:
The patent creates a composite material where activated carbon serves as the stable carrier framework and metal fluoride is loaded as the active component. This composite structure combines the chemical stability of activated carbon with the high adsorption capacity of metal fluoride, resolving the contradiction by allowing both material stability and high productivity to coexist through functional division within the composite.
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 resulting material effectively absorbs moisture from HF electronic gas, achieving extremely low water content (down to 11 ppb) and high purity, thereby preventing secondary pollution and ensuring the performance and yield of semiconductor devices.
Implementation Method 1
the resulting material effectively absorbs moisture from HF electronic gas
Implementation Method 2
subjecting to a crystallization reaction at 140-180°C for 80-120 min
Implementation Method 3
subjecting the metal fluoride-loaded activated carbon material to a deep dehydration to obtain a material AC/MFx
Data Source
AI summary
Provided is a preparation method and use method of a material for deep purification of HF electronic gas. A metal fluoride-loaded activated carbon material AC/MFx·nH2O is prepared, and a mixed gas flow of carbonyl fluoride and high-purity nitrogen is used to deeply dehydrate the material to obtain the material for deep purification of HF electronic gas AC/MFx. This kind of material has fluoride that can form crystal water to form hydrated metal fluoride, and has strong water absorption properties. Moreover, the anhydrous fluoride and activated carbon do not have to face the problem of being corroded by HF, and the collapse of framework structure and the secondary pollution to HF from reaction products would not be caused. The material has the advantages of high purity and extremely low moisture content when being used for efficiently removing moisture in HF.